Datadog startup journey from my perspective:

1. use Datadog, because it gets you a bunch of stuff without having to really set it up, like anomaly detection, which is poor man's monitoring & alerting

2. once you start getting product-market fit and the number of instances you run grows you notice your monthly bill going crazier and crazier and you now have something that starts to resemble an ops team -> migrate to a different product, set up proper monitoring

I've seen that at 3 companies I worked at.