The problems I find with WordPress are:
- WordPress core is missing a ton of stuff you'd expect to be there so you have to turn to plugins.
- It's hard to assess the quality of plugins. They conflict with each other, kill page speed, they break as WordPress is upgraded, and there's tons of bad advice you have to navigate around (I find this problem with PHP in general, where top voted answers/suggestions are bad so you need to keep your wits about you more-so than other communities).
Generally when I'm fixing WordPress websites, I'm stripping out all plugins (I've seen over 50 on one site before!) that have been added by non-technical users, then trying to find the simplest way with the fewest plugins to get the functionality back to what it was.
You can get pretty far with just ACF, a contact form plugin, an optimisation plugin (how is page caching still not built into WordPress?), and coding small features into themes directly.