“To sum the above succinctly, the problem with decent IDE support was not of N * M, but rather of an inadequate equilibrium of a two-sided market.”
The standard story says LSP solved an M times N problem of editors and languages. The real problem was that N was zero. Microsoft sold both languages and editors and was losing the IDE fight to JetBrains, so it had a reason to break the standoff. The protocol was the easy part. The incentive was the hard one.