The evaluation of SPARQL patterns is PSPACE-complete. Which means that for trying to approach the problem of writing UIs (working on a realistic hardware) that

The evaluation of SPARQL patterns is PSPACE-complete. Which means that for trying to approach the problem of writing UIs (working on a realistic hardware) that adapt to different ontologies you need to restrict the set of possible solutions... That is, to limit the number and place constraints on the ontologies you accept. The ActivityPub ecosystem is a glaring example of this. ActivityPub defines a set of baseline requirements (and a basic ontology) that all implementations need to support. Once you meet the baseline, you can use linked data tools to extend the standard. Applications that understand your extension will also interact with it in the UI, those that don't understand your extension usually just ignore it. But you need to specify base requirements (set the baseline for an extensible standard)! You can't just throw totally random ontologies at devs, it won't work. I think this is the error Solid makes.