Let's say Microsoft finds a way to gain a large market share with Edge. Couldn't they cause significant damage to Google if they enabled ad blocking by default?

Let's say Microsoft finds a way to gain a large market share with Edge. Couldn't they cause significant damage to Google if they enabled ad blocking by default? 90% of Google revenue is still ad revenue. Say they got 50% market share. If all of the sudden 50% of internet users started blocking ads, wouldn't that be a pretty bad thing for Google? Like put them out of business overnight kind of bad? While not hurting Microsoft at all? I wonder if Google saw this vulnerability years ago and so they decided to build Chrome to protect themselves.