They got an amazing amount of mileage out of an 8-bit design based on off-the-shelf parts late in the 8-bit era. You can build a MSX-compatible machine from parts even today.

I suppose that's the power of an open standard: it's doubtful it would have flown if it was just a Sony (or Casio or Spectravision or...) design, but uniting basically every notable Japanese electronics manufacturer who didn't have a solid platform already (like NEC) made it viabl.e

So was x86. The strength was that it (accidentally) became the standard, which is what MSX was trying to do. If it had caught on outside of Japan, we'd probably still be running derivatives of that architecture.