There's a difference between justified moaning about business rates and making the (impossible) revival of the High Street to what it was in times past a central political 'wedge issue'. Dealing with high business rates isn't going to reverse inevitable decline, merely ameliorate the rate of decline. Reform are picking an issue which they will claim that only they can solve, as other parties know it's not solvable and won't make that promise. (Well, if they do make that promise, they are simply deluding themselves that their unicorns are more attractive than Reform's.) It's probably a good bet that people will vote for unicorns yet again, because they want to be lied to, and it's more comforting in the short term than accepting reality.
Reform need another 'wedge issue', now that we've left the EU, and immigration has collapsed. Obviously I'm not in the Reformy bubble (any more than their supporters are part of my wokey-liberal bubble), but I'd be amazed if the High Street & pub thing isn't plastered over every single social media channel they inhabit. Well, that, and people with brown skin needing to be deported, obvs.