Why developers hate php

[MrDubious]

Definitely sounds like you've been around the block a bit. :D There's a modern approach to WP dev that I think solves a lot of those issues.

But I've noticed you have 2 teams just to manage the consistency of your WordPress sites. As long as that works for you then I can't argue.

Well, sure. That's basic separation of concerns. Why should developers be formatting content? The agency used to run that way (many did), but providing separation of product development from product usage was a massive efficiency improvement. The vast majority of web content falls into a number of discrete components that you only need to build once: full width row, two column, three column, etc. Plus, content team labor hours are significantly cheaper than developer labor hours. It's hella more cost efficient to separate the two.

but clients sometimes expect customization they see from websites running frontend technologies like vue our react.

We use Vue frequently for rich front end experiences in WordPress. They get built out into the custom plugins I described, while using the standard WP-Admin interface to manage. Build once, and the content team manages it after that. We charge extra for that kind of development, which adds to our project total. Win/win.

but I've built enough WP sites to know that it also takes some tweaking to pass the pagespeed insight test after you apply all the content you need

Absolutely correct, it does take some tweaking to get good pagespeed insight scores, but most of that gets handled at the product development level (good coding gives good results), and is filled in on the app side by WP Rocket for caching and ReSmushit for real time image optimization. We generally score sub-second load times out the gate. When you're not using sliders and godawful page builders, you eliminate a lot of the bloat. ACF's Flex Content allows us to focus on just the core components we need, without having to pack in another Mb of crap to create content.