The real reason rewrites to fix tech debt used to fail was that it took too long to get to feature partity & the goal posts moved constantly while you were on the rewrite team.
The sunk cost of existing code is no longer considered in a rewrite.
Maybe it was hard to write in the first place, but it is not hard to rewrite anymore, as long you've got decent tests.
The real reason rewrites to fix tech debt used to fail was that it took too long to get to feature partity & the goal posts moved constantly while you were on the rewrite team.
The sunk cost of existing code is no longer considered in a rewrite.
Maybe it was hard to write in the first place, but it is not hard to rewrite anymore, as long you've got decent tests.