How often you have to take algorithmic complexity into account depends on what level of the stack you're at, but even at the application level, I think understanding algorithmic complexity is still important.

I was working at Company X around 2013, and we had a Rails ecommerce site. Trivial in the algorithmic sense. Had a contractor that pushed a change that somehow made everything crawl. When we did profiling together, it turned out he had written an O(n^2) algorithm when looking up country codes or something. Sometimes, there's no off-the-shelf library, and it's the minimum a dev should know not to do.

I'm not saying it should be a maniacal focus, but it should be taken into account. Of course, it's with judgement. We get shittier and shittier software if it's not taken into account at all.