Competition and the size of the market are not always correlated.
The superior strategy is to maximize returns against efforts, not minimize potential for competition.
The essential argument is that a small market provides small returns therefore go after small markets is not the same as proving that the returns are better in proportion to the cost, in time, resources or opportunity.
Most large markets are divided in following a Pareto distribution, which is to say the winners dominate. You don't have a pie divided between competitors, you have most of the pie going to 2-3 players. Be a player.
When you see a large number of 'competitors' in a market, as often as not the market fragmentation is on the buyer side.
Again, I don't buy the small market simplicity argument, and I especially don't buy that small markets offer the best returns for effort. There is an abundance of large markets, many of which are underserved.
If you see an opportunity to squeeze a little market with a CRUD app, by all means, don't let me stop you, but I don't believe that is a superior strategy.