There are definitely a bunch of overlap though between the two, most notably in session replay. Honestly if one of you could combine application analytics with monitoring, it would be a fantastic one stop resource. There is no reason in my mind why these two areas should be separate. Both are basically logging events of different types.
Implementation-wise, I agree. You run into similar engineering challenges in both cases. From a buyer/persona perspective it is very different as you go up-market.
