They do want to advertise but it's precisely because of cancel culture that they're now pulling advertising, companies are just as scared of being cancelled as people are which is why they too play along with the leftist/woke agenda.
Cancel culture is a kind word for it anyway, it's ultimately just censorship. Whether it's blocking funding, blocking services, shutting down speakers at universities, social media banning, suspending, shadow banning, de-monetising etc. It's all just aimed at blocking and suppressing voices they don't want the masses to hear.
If their ideology is so good they wouldn't need to shut down debate and competition.