What I think has changed is that many people have a hard time staying engaged on other peoples' turns. Since that itself -- other people having turns that take a minute -- isn't the new part, I have to think the problem lies with the players. Some people can't stay off their phone or opening another tab when playing online, and can't seem to be engaged in someone else's moment.
I don't think it's as simple as this, I think it's just that people derail into different stuff now.
For me, the biggest "long turns" example is Champions: New Millennium - the FUZION variant of Champions. It was terrible. Turns went on forever - worse than Champions itself even! And people absolutely got bored and annoyed on other people's turns, despite it being 1997 - but they were reading books or engaging in table-talk or w/e instead of opening phones.
I also don't think phones are as much the issue as families and work
via phones. In like 2010 or 2014, just phones were the issue because people were much less disciplined about them, but in 2024? Nah people are better now. No-one is opening a mobile game or scrolling Twitter when we're playing a TTRPG (at least not in the groups I play in). But people are absolutely getting messages from spouses, kids, work, and so on, stuff that they can't always entirely ignore. (The work stuff particularly because people tend to be senior now, given we're in our 40s and thus sometimes have things we have to respond to even in evenings/off-days, oh to be a true European!)
But my point is, I don't think this is new the way you're suggesting it is. I think really long turns have always been bad, and always frustrated and bored people, and always caused derails. It's just more obvious now.
I particularly say this because when something genuinely exciting is happening, you don't see that - you're saying "people can't be engaged in someone else's moment", but I absolutely do not see that. When a character is genuinely "having a moment", people are engaged, are paying attention! But when some guy is dithering over various options, or discussing the situation with the DM, or trying to work out how his tediously complex abilities work? Yeah people check out. But they always did!
or whether it's about the players literally having shorter attention spans (not always literally ADHD, but plausibly at least sometimes)
I have severe ADHD. ADHD and attention spans in general are 100% not the problem here. I've never had difficulty paying attention in a game
if there's anything to pay attention to, and some guy's overly complicated VP pool being reallocated to use a different power is not something to pay attention to.
DMing is important here. Yeah, if you're playing a complicated game, and the PC has complicated and time-consuming abilities you have to work out, and that might be minutes of talking, once you've worked them out, then you have to sort of wake everyone up! That's a DM skill! That's important. I've possessed it since the 1990s, but I know a lot of DMs don't, because I've seen them not do this - they just resolve the action in the same lowered tone they've been using to discuss the rules. No. Wrong! Don't do that! Once the action is going, raise your voice, use a stronger tone, people will look up from any distractions, and
then describe the action. No-one will miss it that way. They'll just miss the boring and genuinely pointless-for-everyone but the player & DM rules-discussion.
For clarity, I don't really care about how to have a fast paced game. It is about how it is okay to slow down and enjoy things like tactical complexity and nuance, for me.
So, in games where there is genuine tactical complexity and nuance, and THAT'S what is slowing down the turns, I don't see the disengagement you're describing. This was one of the things I liked about 4E - people didn't get disengaged in the way they did in 3.5E, because what other people were doing mattered much more to what they'd be able to do next turn or the like. Where in 3.5E it was often largely irrelevant (I don't want a detailed argument about this specific example btw, anyone trying to engage me on that, miss me and just mentally substitute whatever games you think this would be true for).
What I see causing disengagement is long turns where rules or rules possibilities or powers or spells or the like are being discussed, essentially just player on DM. And I accidentally a found a solution to that years ago, which is just like, once you're about to resolve the action, speak in a way that brings people back. Project, use a firmer tone, etc. It's actually kind of totally fine if people check out a bit whilst you're working out how some complex power works.
Also, I think games which let some players take a lot more, and a lot longer turns than others are well, not well-designed as TTRPGs. Champions genuinely has a problem there. It's not "tactical nuance" when one PC gets three turns for the one turn another one does, and not only that, but that one three-turn PC's fiddly powers are significantly harder to resolve, and that particular player has a bit of a case of analysis paralysis re: exactly what they're going to do. You can render speedsters and stuff rules-wise without just giving them a bunch of extra goes!
I think it's very important to accept this isn't just "Players be sucking these days", but to realize some systems are just kind of problematic for this, and that DMs also play a role in how this plays out, and can help to make it less of a problem without trying to alter player behaviour particularly.
(Again, my experience is that people are much better about not doing things like scrolling Twitter/Insta/etc. and not reading the news and so on now than they were in 2012, say.)
Generally the issue with complex RPGs isn't the complexity itself, it's the fact that nothing happens as a result. Yay, someone's HP number changed! Let's continue doing the exact same damn thing we were doing before!
Very true. This is kind of the distinction I saw with 3.5E vs 4E - in 3.5E, often all that happened on a PC's turn was a monster's HP went down, and it's like, okay, does that really change anything? No. Whereas in 4E, monsters were getting slid every which way, suffering conditions that enabled abilities in other PCs, PCs were repositioning in ways that had tactical important and so on, and people paid a lot more attention as a result.