Earlier quoted context omitted.
If you have more than two parties then the winning party may have less than 50% of the votes. That's just how the math works out. Somewhat ironically, given your arguments, UK voters decisively rejected a plan to change the voting system to a more proportional one in a 2011 referendum: https://en.wikipedia.org/wiki/2011_United_Kingdom_Alternativ...
Yes, but: the winning party having less than 50% of the votes still feels incredibly undemocratic, as you get a situation where a majority of the voters picked a different choice. Proportional systems give an outcome where a majority of voters voted for at least one of the parties in the winning coalition . Coalitions become explicit rather than internal to parties. The internationalist/isolationist split in the Cons…
Edit: I'd also add that the UK is astonishingly democratic in some respects. It is remarkable that Brexit was implemented merely because a majority voted for it. There are few countries where such important decisions of national policy would be put to a popular referendum in this way and then implemented faithfully. (I was very firmly opposed to Brexit, FWIW.)