The problem with generic deployment services like this is that they don't account for scalability.

Different stacks have different requirements. I built my own deployment service for my open source project/stack specifically so that it would handle scalability too. See https://baasil.io/ I know Laravel followed this approach too with https://forge.laravel.com

I think using more sepcialized deployment stacks (as opposed to generic ones) is the best approach for non-trivial apps.

Though I guess if you use a microservices approach, you could have a different deployer for different kinds of services.