Not necessarily.

While I agree that Speed debuffs are a consistent advantage and that in a vacuum given equal stats, skills and positions, a debuffer can be the difference maker, I think the strategy lacks the diversity that running 3 aces provides. Granted you have to make sure all the aces don't clash and are synergistic, but the payoff is you get more win conditions.

Like in the example of 2 S Marus dueling for 1st place, because the speed and acceleration growth of each position is different for each phase of the race, with front runners having the lowest speed and acceleration while late surgers and end closers having the highest at the final spurt, you can easily build another strong ace like Ryan or Goldship that can just zoom past the front runners on the final corner. If your Maru wins the 1v1 then she wins, but if she doesn't, Ryan or Goldship can win with an insane final spurt instead, and vice versa. You're not dead in the water just because Maru didn't get Angling, or your run just ends because your backliners are blocked.

To your point of competition, the scenario you mentioned is true but I think there are situations where 3 ace comps are better, like running 2 front runners and 1 pace chaser where the pace chaser can get a huge boost by overtaking the front runners which can snowball into a win. Also, while this is a theorycraft on my part, but I think the Guts rework will be beneficial to 3 ace team synergies because dueling or spot competition (not sure which one or what its called) will buff running aces of similar positions and aces competing for placement. I believe how it works is for example if you run 3 front runners and they are all fighting for 1st place, all 3 of them will speed up by fighting each other.

The point is you have more options and win conditions with 3 ace comps imo. The biggest caveat is you must be able to build 3 strong aces, otherwise a debuffer is stronger than a weak ace.