I'm going to disagree here. Recording is an open loop process, nothing from the "PA" or "monitors" can bleed back into the mic whereas a live situation is a closed loop process... as soon as you close the loop, bleed becomes an issue. That's why an omni mic might be a great option for studio but not so great for live.
I guess I'm just spoiled by the two rooms I work in. I've never had bleed become an issue. I always take it into consideration. That's why I use mini-condensers in the grand piano with the lid closed. I'm still getting some low end bleed through the soundboard on the piano, but after working in the room for 13 years, I know how it's going to react. BTW... The piano mics are omnis. I use omnis in the pit as well. Sometimes I use the countryman B3s on strings. DPA makes a great mount for them.
Granted, it wouldn't work for a rock show. But I am blessed in not having to deal with that much, unless of course, it's my band, which is all rock.