It’s a specific type of thing, but it’s not a brand. Nobody owns the trademark for Bitcoin. Anyone can buy, sell, or mine Bitcoin. It’s no more a specific product than dollars are a specific product.

If they added a Bitcoin logo, then you’d see every other crypto lining up to get their logos permanently installed on every person’s devices, too.

Is there a problem with that? This isn’t “advertising”, these are unicode symbols. There are unicode symbols for all kinds of things. Every currency has unicode symbols, why not cryptocurrencies?