Even if you personally are capable of enforcing work/life separation there's zero chance an entire company will when so many people already fear the Performance Review looming over their head.
I just don't see an every-waking-hour workday dystopia ever happening if the industry goes more remote.
I think this may be the key. I work in-person in a Tech BigCo main office, and emails/chat/posts/pings are already a constant on any night or weekend. I don't know how it would be possible to avoid when we work with teams on every continent — some external so their working hours are non-negotiable. It's cool if you can be a good enough performer to disconnect at 5PM and never contribute to the problem by reading or responding. Some people have to—or think they have to—do that show of "putting in extra effort" to make it by their next performance review.
I'm a "WFH Apologist", really, but I'll readily admit it's not for everyone. Many people genuinely like in-person socialisation at the office, others can't separate 'work' from 'home life', and we could go on forever on potential issues. Which is why no one will ever see me advocate for all tech companies to go as remote as possible normally - that would exclude a pretty wide pool of potential candidates.
Also, as someone who’s worked remotely before: working longer does not mean more work done!!! in fact I think I can safely say you’ll get less done if you start working more than ~7 hours a day because then your workspace and relaxing space start mixing together (and your brain will force you to relax sometimes.)