You're right on some points, other points don't match up with my understanding of the issue.
Chrome was a much better browser compared to the default that came installed on Windows, and certainly if someone is going to switch away from the default they will do it towards a much better alternative, on that we agree.
However, despite how much I think Google as a search engine has declined in quality, I still find them to be significantly superior to the alternatives, such as Bing and even DuckDuckGo (which I believe predominantly makes use of Bing) and that people will switch from whatever default search engine Apple sets to Google.
You're also missing the power of reputation. It takes time to build a good reputation, and it takes a really long time to overcome a bad reputation. MS built itself a really bad reputation, especially with browsers, so even if (hypothetically speaking) Edge were as good as Chrome now, it would still take a very long time to overcome the terrible reputation they earned with IE.
Chrome was a much better browser compared to the default that came installed on Windows, and certainly if someone is going to switch away from the default they will do it towards a much better alternative, on that we agree.
However, despite how much I think Google as a search engine has declined in quality, I still find them to be significantly superior to the alternatives, such as Bing and even DuckDuckGo (which I believe predominantly makes use of Bing) and that people will switch from whatever default search engine Apple sets to Google.