I assume the person you're replying to is talking about the Filibuster and supermajority requirements not the direct election history. The filibuster is a senate rule not a constitutional design, so it wasn't part of the "design". Maybe they're both different ways of adding veto points to the same effect, but I think spoilers as "explicit design" is probably not how I'd describe it.

https://en.wikipedia.org/wiki/Filibuster_in_the_United_State...