FrogReaver
The most respectful and polite poster ever
The rules dont say that, though. They say "clearly seen" and leave the definition of "clearly" up to the DM. So, your claim that "he can see you to" isn't the rule, it's your ruling.
Which is your preference and your prerogative to run it like that. The rules, however, fully support ducking in and out from behind a you-shaped rock every turn, provided the DM rules that way. This is the beauty of the stealth rules: they left it open so that permissive hiding is as RAW as limited hiding.
That ruling is supported by the rule that enemies are aware for signs of danger in combat. Is it spelled out explicitly?. Absolutely not and thus this discussion. But you can't pretend that enemies staying aware for signs of danger in combat doesn't at least offer some support to the idea that hiding in combat by default and without DM exception is hard.
You see I agree it's the dms call. It's the notion of "nerfing" and that somehow the game without DM exception means hiding in combat is very very common that I take issue with. Stop framing it that way and we may find some common ground.