It's still a bit funny that there is only one pro singles set ever to have the result 13-12.
They really had a hard time making up their mind. I thought that was a good solution, I don't really get why they removed that rule.
It was basically a direct overreaction the 2018 Isner/Anderson Wimbledon semifinal, which bled over into some minor logistical issues with the Djokovic/Nadal semi everyone actually wanted to see not being finished on the Friday because of Wimbledon's unique curfew rules meaning they don't have full on night sessions and they just stop playing at 10 PM local time or something.
One very bad argument used a lot at the time is how it was unfair to the players if they played a match that long because it would affect them in future matches, which is just a clear skill issue, and if you don't want to be tired in the final, you just shouldn't play a 7 hour semi.
The other side of it is that value of extended 5th sets basically got ignored completely, in that it adds something truly unique and that every match that would have gone from 8-6 to 70-68 in the 5th now becomes a completely indiscernable 7-6 where any potential for a single match to become an epic story of it's own is completely diminished.
I guess one more reason to do it is to have more predictable finishing times, or at least to make it clear to the audience the finish line is in sight at a certain point when going to a 5th set, which is much more in line with all other sports, and I can't really think of many sports where a match could go on almost indefinitely.
But really, the most obvious reason is the main match that caused it was an Isner-Anderson match, and nobody likes watching Isner and Anderson fail to put returns in play for 7 hours straight.
That's why I have always advocated for just banning John Isner from tennis altogether rather than breaking what's not broken and making 5th set tiebreaks a thing. It's like having a scratch in the paint of your living room and fixing it with a sledgehammer.