Avoiding all that "fancy unicorn stuff" might not slow you down but it will slow down the next person who picks up your code but who cares that's their problem.
You must come from the same school as "who needs tests they're a waste of time".
You must come from the same school as "who needs tests they're a waste of time".
Oh and no, I'm not from that school. But having tests doesn't mean the tests are any good. You can have loads of methodologies, patterns, principles. If you can't tell when to use a Factory Pattern, or how to implement SOLID, then it doesn't matter how much you like, or want them.
Design patterns can definitely be abused and pragmatism is important when deciding whether or not to use them. I would say though that implementing SOLID is certainly achievable if writing from scratch but harder when refactoring code that breaks those principles (usually badly with no tests or poor tests).