You are obviously being biased with your own personal taste. Objectively they are one of the best live bands out the there and they do usually shift a load of tickets, they sold out ally pally in 2021 on their arena tour, this year they did a 3 month uk tour of small venues and sold out the same venue 3x instantly. They also headlined Slam Dunk this year and really put on a great show. They could be pushed to a sub, if Architects can then Shikari can.
they haven’t sold out Wembley yet because people who like them have probably seen them a lot lately. Their new album hasn’t really taken off either.