Semantic UI is a production ready app UI framework.
Bot have legit uses, but I think they cover a bit different use-cases.
> I'm certainly not going to spend much time optimising it. if it's a quick hackish tool for your team then it's certainly fine
Every use case is a bit unique. I've built apps with bootstrap, but I gradually removed it later because I simply rewrote everything I used from it.
As an example, DataTables works out of the box with Bootstrap and Foundation, but not with SemanticUI. Same with Select2, Symfony, JetBrains IDEs.
The more bespoke your application, the more Bootstrap will either be useless or counter-productive. But if you're building a standard UI, Bootstrap is great. It's easy to find junior devs who can use it, and there's good documentation and support.
I've never heard this recommendation. Why would you waste time on a framework you are never going to deploy to production?