Do we need 2 dBs of gain reduction ? 5 ? 10 ?
The point is, it heavily depends on the nature of the signal, and of the context.
Compressing guitars can make sense, but each case is different: A funk guitar may need quite a lot of compression, while heavily saturated guitars usually don’t.
A synth patch may also need compression, but we should also consider getting back to tweaking its enveloppes settings for a cleaner result.