I mean, you could create one just for games you want to keep on the DL, discreetly? Not perfect, but given the options, it's at least a good one.
It's not really a good one for me personally when Steam is my primary method of communication for some of my friends and family. Switching accounts any time I want to play one singular game, and thus losing the ability to communicate with said friends and family for the duration, just isn't practical.