Effort matters, but there’s a limit to how much DIY should be required. Take MyBB as an example: it still lacks a built-in alerts system and a proper mobile interface. These are fundamental features that should be included by default, not something the forum owner has to implement themselves.
I don't quite agree on one aspect - the alerts system. Alerts systems were never originally needed for forums - forums were exactly the kind of place alerts weren't needed, as at least when I was younger, forums were supposed to be something dipped in and out of - you discussed only the things that interested you, and you went back to posts you'd made frequently to check if anyone had replied to you - alerts just weren't envisioned as a core feature needed.
Granted, it's absolutely possible that MyBB could've moved with the times and implemented systems similar to what XenForo and vBulletin have, but at the same time, I like the fact that MyBB has retained a lot of it's "core values" as much - which is that forums are meant to be relatively simple places. Sometimes I think members appreciate a break from a forum/social media/website or whatever it might be that is constantly demanding their attention by notification.