Combine FPTP with the electoral college system and you get arguably absurd presidential outcomes like we saw in 2016, where the winning candidate can receive less votes than the runner up and still win. Huge majorities on minority shares are often found in FPTP systems, because anyone who didn’t vote for the winning candidate might as well have not voted. It can also create the opposite outcomes, minority seat shares in the legislature on majority vote shares.
It’s just a plain bad voting system if you believe the legislature should at least vaguely reflect the wishes of voters.