I mean historically it existed mostly because states had much more autonomy and power, much like a city state or country. Until at least Lincoln that part of the system had a good logic to it. If they only went off of proportional representation they could basically ignore small states needs. In order to get states to agree to join the union, they had to build a country that would give all states a serious seat at the table.
The main reason people on the left hate it so much now is that it currently hurts us, but it’s very much an equity vs equality argument. The system was set up to be equitable even if it isn’t equal. Something the left typically supports and this meme touches on. I think the higher priority fix is the house, as it no longer even does what it was designed to do.