Not necessarily.
Many people prefer the all in one room approach. It has many advantages particularly for one man bands.
Your only real concern is one of sound isolation, and possibly the "sound" of your room.
If what you are recording is not bothered by the recording gear / computers/ extra people sitting around kinda thing you wont have a lot of problem. But if you are recording open mic stuff (or really loud) you may need more isolation. (possibly a vocal / amp booth).
What makes a really good mixing room (symmetry) makes for a troublesome recording room if the volumes are substantial at all. The better sounding recording rooms are as asymmetrical as possible to minimize reflections and standing waves, but there are always some things you can do (absorptive and diffusing) to help.
