We already have Are hosting recommendation requests on-topic? where the consensus was: Web-Apps are OK, but asking for hosting providers is off-topic. Are web service recommendations off-topic? comes to a similar conclusion, but could be misinterpreted in the context of my question here. There's also Is requesting a service (that has a software part) on-topic?
I'd say we need this on a more generic basis, as there are questions popping up asking for VPN providers etc.
So what is our stance concerning questions asking for "service providers" – not WebApps, but things like VPN providers, DNS providers etc – whether they have their own client software or not?