If you don’t share back then sure, it’s a problem. Since I do, I don’t see an issue with using things like Sockseek to build your library first and then start sharing. I had zero flac files when I started. Sldl jump started my library. As I’ve ripped CDs, gained more, and run them through Picard, I’ve been able to build it up even more and share rarer music. Not everyone using projects like Sockseek are leechers and there are plenty of leechers using Nicotine as well. Personally I would rather just not bother with gate keeping leechers and lead by example. (Especially when it could inadvertently negatively affect newbies).

Is there a particular reason for downloading from streaming services? If not and lossless is important to you, it might be easier to use something like Soulseek (via Nicotine) and get flac files. There are some projects like SockSeek that can automate downloads (I used it when it was called sldl to convert my YouTube playlists into a local flac music library).