Alonso never said that an LI team was cheap. But it's not a stretch to say that every team naturally turns into an LI team right now, due to the limitations of the salary and potential formulas.
It used to be that training a HoF players primary skills to the cap took a long time, at least for backcourt players. This acted as a natural counterbalance against loaded IS/secondaries, because better primaries are obviously preferable. But now we have youth trainers and the gym supercharging a players development curve, so they approach the cap with several seasons to spare.
So because IS costs nothing in the PG/SG/SF salary formulas, and not much more in the respective potential formulas, managers are wise to spend the extra time they have boosting IS (and for PG/SG, ID as well). This isn't new logic, but circumstances have allowed it to become the meta to the point where certain managers may now look at 15 IS on a guard and say "bah, mediocre!"
Of course you have a point too, players with high TSP for their salary are a lot more expensive to buy than less rounded out counterparts, so clubs can't necessarily afford an entire team of top NT level talent, even with the merchandise subsidies.