It's not, but it's Microsoft's problem. The reason Edge exists is to try to win back market share from Chrome. The reason Chrome exists is to perpetuate the Google ecosystem by making Google offerings cross-platform, but more importantly Chrome-platform -- not just Google ads.

But you're right, Microsoft will have to decide which one is more important: driving ad eyeballs to Microsoft properties at the expense of Google properties -- or -- decreasing the share of users using Chrome and by proxy, the attractiveness of Google's integrated cloud email/drive/docs offerings.

Microsoft adding an ad-blocker by default, while also owning an ad service seems to be a set of conflicting interests.