No need to be dogmatic, there are valid reasons to use these.
For example, we have some heavy reports that take a few seconds to load, so we show a screen similar to this while we crunch the numbers.
For example, we have some heavy reports that take a few seconds to load, so we show a screen similar to this while we crunch the numbers.
My issue with whole-page takeover loaders is that they lose your control and spatial sense of the app. You can't, for example, page away if you decide the report is taking too long to load, or you went to the wrong section of the site when hunting around for a piece of information.
This can likely be extended to only be utilized on part of a widget. If it's something like an ajax call you can easily add an option to cancel the request e.g. underneath a spinner.
For your report example in particular the service could be developed in such a way that the processing occurs independently of the user session. You can mix this in with an additional request which returns the actual progress of what has been calculated in the report such that whenever a user browses to that page, they can see just how much time there is to go before their report is generated.