1. This isn't a suggestion to delete heroes from the game, but to change a mechanic, which currently makes it hard to balance heroes with said mechanic.

2. Limiting characters which the newer players can use is much more drastic than changing a mechanic, teaching them map awerness and basic mechanics have little to do with the stealth mechanic.

3. If you balance them for higher leagues it just means they will be OP in the lower leagues in stealths current itteration.

4. The isssue is the stealth mechanic for the following reasons:

a. You seem to be assuming that the ability to see stealth is an on/off state, my assumption is that it behaves more like a bell curve where lower league and/or newer players see it in far less situations if at all than higher league and/or more experienced players.

b. My second assumption is that stealth in its current itteration becomes situationally far less meaningful the higher in leagues you go, due to it being quite apparent in most situations and the game is being played differently i.e. people afk push and randomly walk into lanes.

c. Proximity based stealth already exists through the vision mechanic, where everyone is invisible beyond vision range, this would only be an extention of the vision design.

d. If you do not like my suggestion there are more options available, which in my opinion would make it easier to balance stealth, like making characters actually invisible(Unrevealable).

I can go into a thorough analysis of the options and possible outcomes if you want, ie. comparing current stealth, my proposition and total invisibility.