> everyone else uses it soon enough.

Unfortunately in this case, ASICBOOST is both patented, and adds a fair bit of complexity to mining hardware. Both these problems have the undesirable effect of increasing the barriers to entry for new asic manufacturers - an undesirable thing from the point of view of Bitcoin users.

You're quite correct that shortcuts are irrelevant, but the reality of manufacturing makes the playing field a lot less level than we'd like.