Because that's not what Ineos or Ratcliffe have done in literally any of their other sporting endeavors. And it's not the "normal" thing to do. I'd say at base level it's fair to assume Ratcliffe will be a normal owner until proven otherwise. Glazers are shit owners and completely ignore the football side. Whatever internal financial things happen, I'm not sure on what is standard and what isn't, but what isn't normal is an owner who regularly takes money out of a club and invests 0. Ratcliffe and Ineos have done the opposite of that everywhere else, which is also what the majority of owners have done. The Glazers are the exception in how they do things. Your fear is "what if the new owners are in the 1% of garbage tier owners again?". It's not a rational thought. I mean it might happen, but we literally have no reason to think they will be vs anybody else. That risk exists for everyone.
Brand value grows until it doesn't. Nothing to say it grows endlessly. The football cash cow has stalled the last few years with so many clubs regularly turning in losses and not being the endless exponential growth like the 90's, 2000's and 2010's. That's why you see many of the big clubs looking at investment sources or full sales. Some think it'll still grown others think it's peaked or will slow down and the costs won't be worth it anymore.