I've seen this done on private servers with the old API that allows you to macro a significant amount of decision making and automate healing, decursing, etc. With the newer API and having to micro everything yourself I doubt it. Even a relatively simple raid like MC has a ton of movement required, spreading characters out or into stacks, decursing, taunt swapping, CC and add management, etc. Simple mechanics when dealt with alone but trying to manually manage everything by yourself or even with two people would be rough.
Also, casters deal pretty poor DPS in early tiers. Most of the fights in MC benefit a ton from having stacked warriors and rogues to cleave adds. Stacking mages would make things easier from a movement perspective but it would reduce your DPS considerably and make many fights a lot harder. According to DPS logs recorded in vanilla preraid BiS warrior in MC averages around 480DPS compared to 360DPS for mages. That's largely due to being able to cleave/WW adds.
Mages are brought in MC mostly for decurse and polymorph (which is also very difficult to track from multiple mages with no focus target.)
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