As I mentioned before, this speeds up builds because the binaries are smaller, and less data needs to be written. The only effect is that we cant attach a debugger to Lemmy, but we dont do that anyway (and if so, its easy to change the value). Crashes still print full stack traces.
A quick comparison with only one build each:
debug = 2 (default): clean build time: 3m 17s binary size: 450M debug = 0: clean build time: 1m 42s binary size: 90M
You can imagine that the difference would be even bigger for incremental builds.