If you want to be timed on the uphill and downhill, there's this thing called "cross country" that might interest youSeems pretty lazy/full h o m o to only time the downhill sections, goes right in line with fat fucks and overbuilt bikes.
I'd say that, over here at least, 'enduro' is probably a lot more in line with how most people ride. The uphill stuff is the shit you have to deal with to do the actual fun stuff. Enduro racing matches that. Some of them do have timed stage starts so you are effectively timed on the uphills/liaisons, but it's more that you have to complete it within a certain time rather than having a fast time up it.
It's fun seeing people create some straw men to knock down here, but that's along the same lines as me saying that people who prefer single speed hardtails are just pussies who create arbitrary restrictions on their bikes to give them an excuse to be slower on trails than faster riders on long travel full sus bikes. That's clearly not the case, and in much the same way if you ride other places/with other people you'll find that there are plenty of people who rip on enduro bikes rather than just being tubby rich people wobbling their way around blue trails. The majority of people out there don't have great bike handling skills simply because they haven't spent much time honing them in like trials riders have, so it's sort of to be expected that as a result a lot of them will struggle if things start getting tricky.
One of the local groups I ride with here has people who race/raced EWS, or won their categories in the national enduro champs, and it's insane how fast they can go. Even on relatively basic sections of trail they can just squeeze more speed out of them (or more realistically lose less of it). Longer travel certainly helps by taking the worst of the hits, but there's a lot of intricacies in their technique hidden away in how they operate that allow them to go that fast. It's the same as trials - you could jump on Carthy's bike and you won't suddenly be upping to front head height shit, and similarly if I jumped on an EWS pro's bike I wouldn't be able to hit the steep, tech stuff they hit at anywhere approaching the speed they hit it at.
Just on that video of the EWS you posted, the Tweed Valley isn't really a great example of a typical EWS. The stages they focussed on in that video are pretty niche (to the extent that most riders were cutting their bars down way narrower than normal because of how tight and awkward those trails are). Those particular trails are very well established trails in Scotland (which pre-date "enduro") which is why they're so worn in.
Anyway, all that stuff aside, as I chatted to you about on Instagram dropper posts will benefit almost every bike they go on. Some roadie even fitted one to help him win a stage on a pro tour race with more emphasis on the descents. If it even adds to something as low on the 'technical' side of things as road riding then for off road stuff it makes even more sense.
29ers are a lot better now than they used to be, and feel a lot more fun than some older ones did. Tyre width/casing/compound will play a big role in that, so if you fit some heavier duty tyres it'll feel more planted and stable at the expense of being more agile and playful. I prefer 27.5 personally, but again that's probably more a function of the trails I typically ride. The hills in my part of the world tend to be steep and there's more of a focus on tech stuff on them, and 29ers just feel a bit weird to me for that kind of thing. As before though, those enduro racers that I ride with make their bigger 29er bikes rip around them so it's clearly not the wheel size that's making the difference.
If you're specifically looking for a hardtail bike there's a decent range of bikes out there that should suit you, from more XC-orientated bikes from brands like Canyon to more 'hardcore hardtails' like ones from Ragley, the Kona Honzo LSD, to an extent the Commencal Meta HT AM (which I had, and enjoyed riding a lot) and more. It's also worth bearing in mind that a lot of frames now use a ZS44/ZS56 headset setup, and it's easy enough to get anglesets to suit those that can affect the head angle +/-2° or so. It means you could slacken out the front end of an XC-orientated bike if you wanted to make it more capable on descents, or vice versa on a slacked out hardtail if you wanted to make it a bit more playful on flatter trails. FWIW, I slacked my Meta out by 2° and on the steep stuff here it made a huge difference. It meant the front end was a bit more vague on steeper climbs, but the benefits on the fun stuff outweighed the negatives on the tedious stuff for me.
Slightly contrary to what some others are saying here, I wouldn't worry about the standard groupset stuff toooo much. It's easy enough to switch stuff out further down the line. My Meta came with some basic SRAM stuff (I can't remember way) on a Shimano spline freehub (not SRAM XD or Shimano Microspline), and over time I upgraded the different bits of it as and when I needed to. On the whole cheaper modern stuff is still going to feel better than worn older stuff so it'll probably still feel like an upgrade, but if it's 12spd you will find you'll need to spend more time faffing with it to keep it shifting perfectly. There are always second hand deals out there (the setup I have now is largely second hand) that you can keep an eye out for and upgrade as and when they pop up, or even just pick up a mix-and-match drive train setup to suit your budget. There also some wild cards like the Microshift Advent X stuff that seems to work really well (at the cost of being somewhat heavy), but be really cheap.