LOL, that's not how math works. "10%" is not the same thing at all times.
The difference between needing 19/20 and 17/20 to hit means you're doing TWICE as much damage over time with 17. It's NOT only 10% more damage, and this difference is extremely noticeable for a player. Saying "2 extra hits every 4-5 combats" (a misnomer to begin with) is not accurate representation.
Similar for things like haste in a real-time game. If someone has "weapon delay decreased by 50%" (2 sec weapon delay --> 1 second) they are doing 100% more damage, not 50% more. If you have a "25% decrease" you're doing 33% more damage. A 67% gap, not just a 25% gap when going from "50%" to "25%".
Yes. I know you(general you) can twist numbers to make them sound impressive. 33% sounds impressive until you realize you've only gone from 2 to 3 points of damage. That 1 extra damage is nearly worthless, but hey, 33% sounds good so we need it!!!
It boils down to 10% being 2 extra hits on average in every 20 swings. 2 extra hits every 4-5 fights. At low level(and most campaigns never even reach 10th level) you aren't fighting a bunch(or even any) of stuff with 23+ AC, which is what you would have to be fighting to need that 19 to hit. You have +2 for your 14 and +2 for proficiency at 1st level. How many monsters in 5e even have 23+ at all? Below are all the 20+ AC monsters in the MM.
CR 21 Solar 21 AC
CR 17 Death Knight 20 AC
CR 18 Demilich 20 AC
CR 21 Ancient Black Dragon 22 AC
CR 23 Ancient Blue Dragon 22 AC
CR 22 Ancient Green Dragon 21 AC
CR 24 Ancient Red Dragon 22 AC
CR 20 Ancient White Dragon 20 AC
CR 20 Ancient Brass Dragon 20 AC
CR 22 Ancient Bronze Dragon 22 AC
CR 21 Ancient Copper Dragon 21 AC
CR 24 Ancient Gold Dragon 22 AC
CR 23 Ancient Silver Dragon 22 AC
CR 17 Dragon Turtle 20 AC
CR 23 Empyrean 22 AC
CR 16 Iron Golem 20 AC
CR 4 Helmed Horror 20 AC
CR 6 Hobgoblin Warlord 20 AC
CR 5 Roper 20 AC
CR 30 Tarrasque AC 25(finally found one at 23+)
That's the entire list of 20+ ACs in the MM. Only one is at 23+ and if you are fighting the Tarrasque at low level, no amount of strength is going to help you. Of the seven monsters that come close with a 22 AC, 6 are ancient dragons, 3 of which are good and you probably aren't fighting them. None of them will be fought at low level.
There are only 3 creatures in the MM with a 20 AC that you might fight at low level and none with an AC higher than 20.
It's almost disingenuous to be bringing up needing a 19 to hit. And yes I know there are ways to boost AC with spells and magic items, but it will still be very very rare to be swinging at ACs of 23 at low level.