Suggesting unknown artists is part of the point unless you’re a Beethoven and Mozart forever sort.
A Tidal lossless subscription is $20/month. A Qobuz lossless subscription is $20/month. Yep, it’s a lot but since I’ve been a Tidal subscriber, I’ve about doubled my library size. For $20, you gain access to out of print titles and can have a listen to artists and works you wouldn’t necessarily buy. On balance, this retired moocher thinks its a good deal. The two together are a VSO orchestra wings seat per month for many hours of music.
A switch constrains Roon Radio to your library. Of course, you’ll miss out on new music.
Roon Labs comments on library size determining Roon server processor performance are bogus guidance. The number of simultaneous streams determines processor performance as each has to be decoded for transmission to the endpoint.
Library size determines disk space and the efficiency of the database indexes determines performance searching the local library data. Network latency and service load dominate service catalog search times.
A 10 year old core i3 Mac Mini is my Roon Server. It does fine with 1300 albums and 2 active streams. Note that this Mac Mini is running Ubuntu 18.04 LTS rather than MacOS (out of support eligibility). The machine has been hotrodded with an SSD and extra storage but it is still pretty minimal by today’s standards.
Music is on a Xeon based FreeNAS server running on low end E1250 hardware with 32 GB memory. It doesn’t break a sweat.