The solution is for states to allocate delegates proportionally. That is in the best interest of each state, so it’s not fragile. It can be accomplished one state at a time, so it’s logistically easier.

Isn't this overlooking that each state that does this, especially swing states, does it at their own disadvantage? States that allocate their electoral votes all-or-nothing have more sway over politicians who receive those votes (because the politicians are, in turn, are incentivized to spend their effort on states where the return on that effort is larger, and an effort that wins you 5% of the vote in an all-or-nothing swing state could win you the whole state's worth of electoral votes, compared to 5% of electoral votes in a proportionally allocated state).