The Brexit party *does* have the numbers, though, just as UKIP did four years back. They got more votes, nationally, than the SNP, or the LibDems, did, but fewer seats because the vote was spread out nationally.
In practice, FPTP coupled with the current party system has meant that Labour and the Tories have a lower threshold of national votes needed to get a majority than any given breakthrough party.
We've gone through all this before. All I can add is that it's massively misguided to think that getting rid of parties is even possible, let alone desirable. Politics parties arose from a natural need to gather together people who are more or less in agreement, so that they could work together to achieve their aims. If you get rid of parties and revert to every-man-for-himself politics then it would take exactly a few months before party groupings became re-established again, and that's assuming that people were hanging around.