How are these Smaller Parties Irrelevant in the UK Political System? (EX)

-Support Base may just be in a Specific Place [SNP in Scotland] and only Limited to 1 Election [UKIP Vote had Plummeted in 2017 GE] -FPTP doesn’t care for Parties with Spacial Voting. [UKIP won 13% of the Vote in 2015 GE, but got 1 Seat] -Policies of the Smaller Parties are Subsumed by the Big Parties, giving them Limited Appeal. [Labour wanted the Net-Zero Carbon Emissions in 2019 Manifesto, which Damaged the Support for the Greens]