It's only true for the majority. Exceptionally athletic people live differently and don't represent the norm.
Here's are some examples:
Person A is average in terms of everything and athletic abilities. He scores 50/100 points that includes everything to measure his athletic abilities. He never does LL.
This same person A in an alternative scenario could have lived the life of an athlete before LL, and scored 90/100 points. After LL and 2 years of recovery he scores 70/100 points. He is still better than any average person and better than his own average alternative in this thought experiment.
And from 70/100 points on he can work his way up again. Of course, if his pre LL athletic version never stopped training, and he competes against this ideal version who now reached a score of 95/100, he can't catch up to this timeline. But he can still score 91/100 after LL, and be better than he was years ago, when he scores 90/100 before LL.
Looking at mock ups of people who come here, it represents the majority. Skinny or overweight like a child, and weak relative to the full potential of a man.
Nowadays people have such weak minds when it comes to working out, they see someone who is better than all non-trained people, and they assume they could never reach that level, even though they could. At some point in life, the athlete was average too...
That is why the response "You won't reach your pre LL atheltic level after LL" is a message from average people directed to other average people who check out from the responsibility to recover fully and beyond by labeling it as an impossiblity. You should know yourself in which category you fall.