As it is known, in endgame hulk manages to de age scot by failed time travel. And scot kept his memories. However, the existence of such technology would have huge effects on the universe, almost nobody wants to be old and weak. you can stop death by using this.

From the good guys standpoint they'd have to develop this and release it to the public because it's the right thing to do. This would in turn transform the mcu into a very different experience.

It just doesn't make sense to me that they would ever show this since they're likely never gonna do anything major with it. In turn implying that the avengers either didn't see how many lives they could save with it (which is just really dumb) or that they knowingly chose not to use it (which is even dumber).

They might need pim particles but for as much as hank pim doesn't wanna share his secrets even he (especially seeing his age) should see the moral obligation of keeping millions from death.

And even if you want to say that de aging would be unethicall because reasons, there is a huge amount of good it can do. Example, they could use it to perfectly recycle anything by deaging it to a former working product or raw materials. Tony said that the de aging happened because they moved time through Scot instead of vice versa. This logically implies that you should be able to do it to anything, not just living beings.