Smaller community compared to LaTeX may lead to perceptions of lacking "proper" extensibility. For users needing niche or low-level typesetting capabilities, LaTeX’s mature and highly flexible system may still feel superior. Build-in package manager does not necessarily 100% guarantee full extensibility as in crazy Latex macros ;-) As I said, it is a young project and young company, it will grow in time.

Proper as in widely adopted as https://ctan.org. Yes, great to have package manager. Typest is a very young project and company.