Competition isn't per-se bad, and if we're assuming they aren't using LLVM, what gains are there to using the IR? More front-ends, I suppose. But I wouldn't be surprised if they had more machine dependent behaviour than LLVM IR (which, let's be honest, includes a fair bit), especially for things like overflow detection. There also are pretty bad limitations to LLVM IR's ability to deal with GC roots, which for MDIL will be especially important.