That's an absurd statement.

All of the route planning tools have their advantages and disadvantages. I frequently create routes for cycling and a couple of times I used Strava, Komoot and Garmin Connect for the same route. Garmin Connect always works because it can ignore map data if necessary. Strava and Komoot were not always able to create the route I want (looks like Strava have added a "manual mode" as well).

Most of the people around me use Komoot, it's also my preferred tool now. The information density on the map is great, the POIs shown on the map can be customized and editing works well enough.

Strava is okay. It definitely looks sleek. The biggest issue is that routes cannot be edited in the mobile app, only created. Editing is possible in the browser but really awkward. Try rerouting parts of an existing route.

Heatmaps are useful sometimes, e.g. when I'm abroad and I don't know if a road can be cycled on at all. But the most used roads are not necessarily the best ones. Komoot doesn't have a heatmap visualization but there are comments, ratings and photos of segments.