For simpler projects (like simple front end applications), I usually let developers decide the architecture themselves (I mostly just offer advice). Since in those cases, architecture is not as critical.

I was myself overlooked for promotions for over 5 years (in spite of constantly asking for one). I was better qualified than my managers to be making architectural decisions but they only realized this after I left (since I started a competing project). So I know how it feels to not be given the chance. I even know what it feels like to have an incompetent person promoted as my boss.

That said, it doesn't make sense to put someone 100% in charge of architecture if they don't yet have the necessary skills. Some systems are extremely complex and easy to mess up architecturally so I wouldn't hand off this responsibility unless I knew that the next person would do it properly.