If by coherent you mean "using only facts and opinions that I accept at face value within my world view" then no.

Personally, I think 5 is way too little. But there are probably some markets for various products and services where 5 is fine. I don't think the number matters so much as that there be potential for a long tail of upstarts who could potentially displace a big player quickly. Whether 95% of the market is captured 2 or 22 players doesn't matter, they gotta know that someone is waiting to take their place if they screw up.