You win by winning, you win by having a strong team, you win by having purpose. For me at least I don't think you win by aping the likes of the Lib Dems and The Independent Group for Change. Him and his pals that worked hard to scupper the last two elections.. can they be trusted to deliver anything? Representation and Democracy is severely lacking in the Labour Party. There seems to be a sphere of influence that governs the party that has no self awareness.. or perhaps it is self destructive on purpose.
You win by appealing to where the voters are, not by trying to move them. They're unlikely to shift where they sit on the political spectrum by much, unless over a very long time. There's easily enough "good" people to appeal to, to do good things, yes you may not get it all, but you can't have it all as there are a large chunk of the population who don't want that unfortunately.
You also win, by not losing votes to your direct competitor.
You also win by controlling the centre (by that I mean those almost on the fence, between Labour and Tories), and whether you like it or not, there's loads of them, and loads of them make up LD and IGC. It's better pandering to those, and winning, rather than losing and ending up with a Tory majority, especially in the FPTP system (which is crap).
I disagree they were scuppering anything, but it's fine for people in the party to not agree or to have different ideas, especially when Labours support started drifting down after Corbyn's peak, which was the GE. I'm sure Corbyn had plenty of ideas which loads of the MP's and voters were not happy about, or did not think were working. Either way, Corbyn wasn't working, for one reason or another, even if a lot of those reasons were complete media horse****, but the party need to recognise that they need to win, and need to recognise when someone can't win. Then they either help them, if they're willing to take the help or change, or the party needs to go in another direction, with or without the leader.
Yes, Corbyn came fairly close in 2017 (in vote share anyway) up against a weak Tory leader, but still had comfortably less seats in a crap FPTP system, and we need to play to those crap rules. Then the decline started (even against declining Tories) and they got absolutely battered in 2019 against an even worse leader, not saying anyone else could have won with the brexit lingerers, but it shouldn't have been that big a gap, and would have been less voters to turn if the gap was smaller.
Labour haven't polled ahead of the Tories by this much since they last got elected. They had a 5% lead under Miliband in 2014, but they completely blew the election.