Correct me if I am wrong....the throat on the .22-250 gets eroded with each and every firing. When it gets eroded far enough accuracy suffers. However if one loads long would that not mititage the loss of accuracy? Of course one could no longer use factory ammo and one might well have to load Single Shot, if the bullets are too long to fit the magazine.
No, you are not wrong, BUT, there are practical considerations to be taken into account.
Barrel erosion is the classic "downside" to high intensity cartridges. The throat of virtually EVERYTHING gets eroded with each and every firing. IT is part of the process. Firearms and machines, and while very specialized, they do have some traits in common with all machinery.
Those parts subject to heat, pressure, & friction will wear. Accept that. Your barrel is a "moving part" in this sense. Given enough time (cycles of operation -for a barrel it would be rounds fired) you will get wear.
At some point, the part will fail to function to spec. Stuff wears out. now, where that point is, and how fast you get there are widely variable.
What you are shooting, and how you are shooting it plays a big part in the service life of a barrel. So does what the barrel is made of.
And, it is a matter of degree, and personal use that determines when a barrel is "shot out". A group size that a benchrest shooter would throw out the barrel because of can be better than the tightest group a big game hunter ever got...
Lets say, for instance, you notice that after firing 3,437 rnds from your .22-250 that it no longer produces 5/8" groups, now things hover around 1 inch.
Do you think the barrel is toast at that point? Or do you wait until groups open to 1.5MOA ? Or whatever...
You can gain some additional "life" to your accuracy by seating out bullets to compensate for barrel throat wear, but there is a point where this just no longer works. At some point, barrels wear to the point they are no longer good enough for what you want them to do. ALL barrels do this, what varies is how many rounds (or possibly how many lifetimes of shooters) it will take to get there. .22LR barrels last virtually forever. Low intensity rounds, lead bullets, usually last many multiple thousands of rounds (something like the .38 Special might go 30,000rnds) before accuracy suffers to the point where the barrel needs replacement.
Heat & pressure is the enemy. Barrels fired in rapid fire matches "wear out" sooner (fewer rnd count before accuracy suffers).
Rounds with reputations for being barrel burners are high intensity rnds, with large powder capacitiy compared to bore size. Barrel steel has been improved a lot since the early 1900s.
The other thing to consider is how much you will have spent on ammo, by the time you shoot out a barrel, vs the cost of a new barrel (or having the old barrel set back and rechambered..)
Generally you will have spent more in ammo than the cost of the work. Often you will have spent more in ammo than the cost of the entire rifle!
In an imperfect analogy, neither the tires nor the engines of race cars last as long as those on your family car or pickup truck. People accept that these things wear out from use, why can't they seem to understand, barrels do too?