Right, and as 3 or 4 people have been continuously stating, what the primary issue is, paraphrased.
"It is not logical that a level 1 X has the same stats as a level 1 Y, given the framework of the fluff since forever."
"It is not logical within the fluff/view of the setting, that a level 1 Halfling, is just as strong as a level 1 Goliath, when both are focusing on Strength primarily."
The REMOVAL of the pre-Tasha's system, the REMOVAL of that option going forward for any new Race/Lineage, and indeed with the new edition (whenever it comes), is and will be, the issue.
First: Thank you for taking the time to lay all this out, its a very good synopsis of the "keep it the way it is" viewpoint.
Second: I am editing out some of the quote to save space, not to edit it to make a point.
Let's set a common ground on a couple things. Let's assume everyone is using the standard array to make characters for this discussion, that "stronger" refers to STR bonus, and that we are only talking about official books, and that we are ignoring pedantic exceptions to the general rule like barbarians at level 20)
Creating a goliath in 5e could give you a 17STR. By level 8 you could have that maxed at 20.
Creating a halfling in 5e could give you a 15STR. By level 12 you could have that maxed at 20.
So, the rules at 5e launch said that a goliath can always be stronger than a halfling for 12 levels, but at that time they will even out. This implies that it is physically possible, in the world you are playing, that a halfling and a goliath can have the same strength given enough time and dedication to maximizing the score.
So I am going to present to you two different character concepts that easily fit within the scope of "normal D&D character concepts" and I want you do decide with your own DMs hat as to the players logic of wanting more than a 15STR that the game limits them to so that they can play the character they are picturing.
1. I was always a super strong kid, so the military was a great option when I got tired of working on the farm. I joined the local army and after several campaigns, multiple promotions, and rigorous physical training I find myself booted due to some bad politics. I pick up my sword and shield and go find work as a mercenary. Stout halfling, soldier background, Fighter 1.
2. I was always a super strong kid. Growing up it seemed odd, and that oddness got progressively worse as I got older. Finally mom and dad sat me down and said "Son, on the night you came to us there was a comet of ill omen streaking through the sky. It crashed on our farm, and when we went out to see the carnage we found you, swaddled and crying as a newborn child, amongst the wreckage. We aren't sure where you are from, but we have raised you as our own and hope that someday you find your true origin. In the meantime here is an adventuring suit of leather painted blue with a red S for Samwise on the front so everyone remembers your name". Stout halfling, folk hero background, Fighter 1.
So, what is your GM verdict....can I play a halfling who having spent years in the military or by having a mysterious background allows me to be stronger than the book mandated "very strong halfling" limit of 15? Does it make logical sense that a half a year of adventuring as a "fighter" should add more STR to a body than years in the military or mystical background?
And that is the crux of the opposite side of the discussions argument is. My individual character should have no bearing on what is "normal" for my race choice, and similarly the "normal" for my race choice should have no bearing on my individual character because, as a PC, I am by definition an outlier to the average.