Degreaser...Doesn't it degrease the bearings too, Even if we are careful

I see degreaser at the bike shop. It looks like it would make cleaning my cassette and derailleur a much easier job with a small brush. While it's probably safe for the chain. Wouldn't it wash out the grease for the derailleur wheel and the hub bearings.

I've a feeling the bike shop uses it all the time. Could they be doing more harm then good.