Having a huge market share by itself is not a problem. If you just make a hugely popular product that more people buy without coercion or exploitation, that's fine. It's just people making that choice, and they are free to do so.

What that does do is create an increased onus on the company holding that position not to abuse it. So that kicks the can down the road to disagreements about what constitutes abuse, but just being popular isn't a crime. You'd need to demonstrate actual harm to consumers.

In the case of search, the web search market and the mobile phone market are two different markets. You can't constrain Google from doing commercial deals with other companies in different markets, just because it's search product is hugely popular. Again you'd have to demonstrate harm to consumers.