what alternatives do you find are better when scaling up with more engineers?
Nobody understands the conventions so they cargo cult whatever they found from a blog that was last updated in 2013. Or they find novel and extraordinary solutions to problems that the framework literally already solved. Or they have zero experience modeling things in a database—much less doing it the way ActiveRecord encourages—so every battle is always uphill.
The biggest problem with convention over configuration is when you have a team where nobody understands the conventions. But what else do you expect?
I will happily concede, though, that I do think in that sort of situation that Rails can very easily become worse than other languages/frameworks.