They've tried the Walled Garden approach with 4e and the GSL, with all these big plans for digital that came to naught. And while I'm sure the tragedy that sunk the 4e VTT and Character Builder was a massive part of derailing those plans, I'm not sure they'd have worked even if it hadn't happened. Even the people who like 4e mention that it feels very different from "regular" D&D, and they constantly alienated fans by changing the lore of old settings to fit with their new paradigm.
With 4E there were just so many negative factors, and it's interesting to look at ones which were different and which similar.
1) With both 4E and 1D&D, Hasbro has announced a demand that certain IPs must make more money "or else". I forget what this was called with 4E, but the value was $50m/year, and with 1D&D it's Blueprint 2.0, and it seems like D&D needs to make hundreds of millions, possibly even a billion.
So you have a similar pressure in both cases.
2) 1D&D is designed to be largely-compatible with 5E in a 1E to 2E sense - and as a player of Anciente Tymes I will say it is true you could just let a 1E class/race play at a 2E table and whilst it wouldn't be perfect, it'd be fine, and I think the same will be true with 5E and 1D&D.
So that's very much a reaction to 4E and a key difference. Probably the one that will help 1D&D the most.
3) 4E's VTT and digital initiative had a short timeline and seemingly a fairly tiny budget. 1D&D's VTT and digital initiative also has a short timeline - but not as short - nearly two years instead of one - but it apparently has a gigantic budget, it things are to be believed.
Will that help with success? Maybe, but I can't help but think both projects are on unnecessarily short timelines and seem a bit confused. Esp. if it's true Chris Cao didn't want to buy Beyond.
4) Bad press/marketing. WotC really seem to have done a "hold my beer!" here. I don't think anyone thought they could create more of a stink than 4E did with 1D&D. Everything was going relatively well. They'd even managed to announce a 3D VTT with heavy microtransactions without people rioting. Then Armageddon. A huge trashing of good will, and not just of aging grogs like most of us here. You can see in the places the Younglings discuss D&D that they're also very unhappy about this.
I think press/marketing-wise, considerably more damage has been done to 1D&D than 4E ever took. The advantage though is there's still like 1.5 years before 1D&D actually hits, but good they've gone from "sitting pretty" to having to make up incredible ground to get people back. I mean I had no doubt I'd buy the 1D&D initial set and so on, even if I wasn't super-enthusiastic, but now? Hah.
5) GSL vs OGL 1.X. The GSL was aggressive but tightly delimited. It raised ire and drove away 3PPs, but it was basically just a self-own, because it lead to 4E feeling like it was "missing something" compared to 3E. The OGL 1.X, even ignoring the PR damage seems like it's created a very different legal environment by being vastly more aggressive and less delimited. Ironically I think it may lead to 1D&D getting okay 3PP support, but quite possibly from companies who haven't signed the OGL 1.X. It also has some potential to cause further bad press and enmity towards WotC/1D&D if WotC does actually sue anyone.
6) 4E vs PF1 against 1D&D vs ???. This is a tricky one. Two months ago, I'd have said there would be no new real competitors alternatives to 1D&D, because there was just no motivation to really do that, and by making it a 1E-2E transition you basically don't give much of a reason. But with the OGL insanity, suddenly an awful lot of companies are thinking about this. Will any of them go as relatively large, compared to D&D, as PF1 did to 4E? No. Certainly not. And I doubt that one individual one will be particularly huge - but I do think several with moderate followings could act as a braking force on the success of 1D&D, and ironically the safe-ness of 1D&D may play against it here to some extent.
7) Old settings. 4E alienated people by publishing old settings and changing the lore. 5E has just done a really unimpressive job with old settings (only Eberron got a genuinely good setting book). The FR got the rough equivalent of 1989's Forgotten Realms Adventures, except less fun/detailed with SCAG. Ravenloft got the divisive and arguably under-detailed VRGtR. Spelljammer got the bizarre "cram literally all the rules AND setting into 64 pages" approach, and Planescape seems doomed to a similar fate. So I don't think 5E has really bound people to D&D with settings, and 1D&D seems very unlikely to change that unless there's a Dark Sun early in 1D&D that is also amazing, which seems... unlikely.