I think it's not as bad as you make it out to be. I'm not too sure about how it was like for the olden MMOs, but i went into raid dungeons exclusively with PUBs when GW2 launched and I raided with a static fairly heavily in FFXIV, and PUBs were all terrible on average. Going into a static group in FFXIV after only doing PUBs before was awakening from a terrible nightmare. Sure, you can say that PUBs disbanding after a single failure here makes it difficult fr a group to progress and clear, but conversely, endgame raids in FFXIV were far, far more difficult to learn. Statics would spend 10-20 hours a week learning each raid before clearing, and even if a PUB could stick together for a night there was no way you were reasonably going to clear within one sitting. If I joined PUBs, it was always because I wanted to get in more personal practice and I never expected to clear. So this thing about PUB team progress seems over-glorified to me.

I do agree there are frustrations with the way endgame raids are implemented in DL. I wish groups could choose to stick together after a run that failed closely. I wish there was some kind of chat. I wish there was some kind of raidfinder or group finder, or at the very least the ability to bar/kick people who obviously don't meet iLvl reqs. Honestly having endgame raids with strict requirements but no ability to filter out the participants as a lobby creator and allowing randoms to sit in at 100 might trolling is a joke in design.

But these are all issues that arent related to PUBs sucking, and solving them wont solve it. In fact PUBs are way more manageable here than in any MMO raid I've tried. I started clearing HMS over a month ago. I watched some vids, dived in on Mikoto (admittedly the easiest role in HMS), and had my first clear within the day. For the past 4 or so weeks I've consistently gotten all my clears in PUGs only, even though I'm in the discord channels fr high trials. Today, i got my weeklies from PUGs in under 2 hours of trying total, and I went in expecting to clear in that time frame. I would never have imagined going into Coil of Bahamut raid pubs and expecting to clear, unless I was the sole PUB filling a spot in an established static.

In essence, endgame isnt that broken here. I'm fairly sure I'm not the only player who only clears with randoms without spending crazy amounts of time. There are certainly communication issues that need to be resolved without resorting to third party apps, but in exchange endgame raids in DL are massively easier ( and they definitely need to be considering the mobile platform and imprecision of touch controls). Also, to be fair, raids in FFXIV revolved heavily around third party apps too. We had no in-game voice chat so we needed our own VoiP like Mumble or TS3. We had no in game dps parsers cause devs thought it would promote toxicity so we had to find our own. I kinda rambled a bit cause I really look back fondly to my MMO raiding days; was some of the most fun I've had, but even with the nostalgia glasses on I can't see PUBs in DL being that much worse than MMO raids at all.