I find that it depends a lot on what you're doing. The real problem with WSL is I/O latency.
It's acceptable for relatively infrequent file access, but will eat you alive if you're doing anything that involves lots of random file access, or batch processing of large sets of small files, or stuff like that.
I just haven't seen that as a problem in my day to day as a developer working with Flask, Rails, Phoenix and Webpack.
That's dealing with 10k+ line projects spread across dozens of files quite often, and even transforming ~100 small JS / SCSS files through Webpack. It's all really fast even on 5 year old hardware (my source code isn't even on an SSD either).
Fast as in, Webpack CSS recompiles often take 250ms to about 1.5 second depending on how big the project is and all of the web framework code is close to instant to reload on change. Hundreds of Phoenix controller tests run in 3 seconds, etc..
It's acceptable for relatively infrequent file access, but will eat you alive if you're doing anything that involves lots of random file access, or batch processing of large sets of small files, or stuff like that.