I disagree completely. I downloaded my first torrent months after the first client was released and my latest yesterday. In those 20 years I've never failed to find what I need and never had any problems with ISP(and would use a VPN if I did). I've never felt the need to check out private trackers.
It depends on how niche your tastes are, or how specific you are about quality. Getting Blu-Ray REMUX files for smaller, forgotten movies on public trackers is nigh impossible in my experience. Meanwhile, private trackers gives the community incentive to seed these large torrents with tiny swarms.
It is probably a matter of what kind of content you're after. I do retro game preservation and private trackers are often the only option for certain sets and certainly the most up to date ones.
