Multiple requests on a RESTful-API for just one thing often indicates a lack in the API design, namely the needed resource was not available and therefore stuff needs to be gathered from different resources to compensate for this.
A REST-API that could be easily replaced by GraphQL indicates, that the API was in fact a CRUD-HTTP-API, what is considered an Anti-Pattern among REST-Evangelists.
Also worth noting is, that GraphQL puts responsibilty on the client, because the backing API is reduced to be a datastore that just needs to be queried. REST on the other hand enforces the behaviour of the client and therefore reduces responsibility on it. The client gets reduced to be something similar to a browser.
There are cases the one or the other approach would yield better results, but that greatly depends on the situation.