> You can, 99.9% of the time, emulate linear history with first parent history
Fully agreed, but that requires first of all to understand how this works and second requires you to run commands locally. If you're unfortunate enough to have to use e.g. bitbucket-server at work like I do, you'll always see the full graph, there which is A LOT easier to grok if it's linear. And since that's what's most devs look at (instead of git-log using some extra options) and also where CI-state happens to be reported (green/red build), that's worth a ton :)
Developers shouldn't try to merge branches with wip/wip/wip/wip histories either, that's just garbage. Commit messages are documentation, fix your documentation before you publish.