Many less experienced developers use it as an excuse of not taking performance considerations into account in design/architecture of a solution.
By doing this, they'll notice retrofitting performance to such a design isn't actually trivial.
The ESB team I have to work with, for example, has a hard cap of 8,000 lines (of XML) in a single file due to their shit performance. Why? “Because recursive, immutable code is ‘easier to reason about’”
For starters, I don’t even buy that recursive and immutable cause ease to reasoning, but forgetting that, if it’s causing computers that should be capable of processing files that are millions of lines long to suddenly come to a crawl after just 8,000, we maybe should reconsider this approach.
Bullshit like this really makes me want to leave the industry. The more "professional" and "business" programming gets, the more bullshit happens.