Providing spoilers was the explicitly designed purpose of the US Senate. It's not a one-sided problem - Senate spoilers are also why the Affordable Care Act didn't get repealed in 2017.
US Senator was an office initially designed to be selected by state legislatures rather than by direct popular election like the representatives. To a populist or a party boss, that might count as a spoiler to the will of the people or to the will of those in DC, or to both. But I may misinterpret GP's point.
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.
Not parent but the founders were like folks writing smart contract code, thinking about various exploits and vulnerabilities (that might reduce the wealth of their class) so many of the seemingly dysfunctional elements of the system turn out to be designed deliberately to be dysfunctional. Feature not bug.
They were not thinking about various exploits and vulnerabilities but rather making whatever compromises were necessary in order to form the union. It was negotiation, not planning.
