Well - all PCs get a chance to roll. I used the 2d6+4 method for each attribute (and you get to reroll 2 dice). So, you can get a monk with an 18 and a 17 after racial bonuses.
When someone plays a monk, I usually make sure they have an opportunity to get a bump up in offensive capability. One monk found a +2 quarterstaff at second level. Another gained a blessing that cast Hunter's Mark when they scored a critical hit. A third had rolled for stats and started out with an 18 and a 17 (after racial adjustments). Another found a Headband that set your Wisdom to 19 and gave you Darkvision.
However, I've played monks myself that were built with point buy and were perfectly fine and fun. To me, whether the monk needs a hand up is more of an issue of the perception of the player than it is a true balance issue.... I did one monk that started out with a 16 dex and 17 wisdom ... after racial adjustment and then proceeded to get Fey Touched at 4th level for Hex and Misty Step. They retired at 11, one level shy of getting to a 20 dex - but they were a huge amount of fun.
But if everyone rolls not everyone will be inflated and even if everyone gets lucky, some will be more lucky than others.
Rolling stats is a good way to facilitate a player with very good rolls being able to choose to play a Monk without being very deficient. However that only happens if you choose the class after the rolls. It is not a good way, or at least not a reliable way, to ensure the Monk is competitive with other classes.
If you're worried about stunning strike spamming, just limit stunning strike to once a round, like the OneDnD current play test (though, IMO, that's about the ONLY thing they got right with the play test monk, well that and the 4 elements monk stinks just a bit less).
Ironically, I think this is going to actually improve people's experience with the Monk. The biggest problem with Monks, especially at mid levels is players blow through ki on stunning strike when it is not a wise investment. You don't see that as often with other limited use things like Warlock spell slots or battlemaster maneuvers, but Monk players for some reason want to FOB and SS every turn.
Stunning Strike is often a poor use of ki and FOB is almost always a poor use of ki.
Standard array (15/14/13/12/10/8) or 27 point buy first, assigned to taste.
Next, roll 6d4 for each ability in order, recording the individual die results.
The player chooses one ability to keep all six dice, two abilities to keep the best five, and the other three abilities keep the best four dice. The character receives the higher of the assigned value or the rolled value in each ability.
Sure, it's mathematically possible that 6d4 can produce a 24. But the average of 6d4 is only... 15.