Inflation is the issue. To much befor you can bleed it out via a soft reset and it makes issues with class intervals for MM not being accurate.
It probably wont break the system, but what it would do is make climbing more RNG on teammate skill ranges and thus make it more Grindy with lower quality games.
LP gains would be fine... but LP gains are little value to an extent. You'd Need MMR for it to impact MM, other wise it doesn't address what MM is doing and thou your LP gain is the same your MMR means that your next matches LP is slanted down.
What might work best, When some one leaves in ranked, you get a vote on if they deserve punishment. If team majority says yes that dudes locked out of ranked for a week.
A more mild (wont lose honor.) but inconvenient style of ban to let players know half assed behaviors are not acceptable. if your not able to take a competitive match seriously you have no business playing it.
Then a lower tolerance for players who blatantly state they are gonna leave (or will actively feed). which functions as the standard honor loss and entire game is blocked for a few weeks up to a perma ban.