There have been many macron questions, but not this as far as I can see. Dickey's Learn Latin from the Romans (2018), pp. 5--6, notes that "Latin texts are usually printed without macrons". A simple question: why? Today's Sanskrit (though not Greek) editions, for example, have no phonemic ambiguity.
I am asking for a specific historical reason (which may be one among many; or there may be none). For example, if a leading publisher of Latin editions (like De Gruyter or OUP) has specifically considered introducing macrons but then rejected the idea, I would like to hear the reason. The answer to this old question lists some arguments for leaving out macrons but does not state which, if any, were the reasons that led to the choice.
To throw in a cheeky speculation: any appeals to tradition can be met with the rebuttal "but they're trying to make Classics more accessible!" ---which is true, at least in the UK. Why preserve this surmountable, yet undeniable, barrier to entry?