

You can find the DVDs on rutracker.org. It’s a public tracker.
You can either use a service like google translate or simply put “smurfs 1981” (season by season) in the search.
The DVD releases also include russian audio in addition to english. There is one torrent with all seasons, but it has Russian audio only. There is a decent amount of torrents, just look through anything that says “mediainfo” to double check that English is included (original audio track is almost always included, I was surprised to see the full compilation without original English audio).
Private trackers also have this show (all seasons).
Interesting, I’ve never used usenet (no pun intended), but this does seem like a pretty big drawback.
I speak fluent English, but if I am not in a mood for subtitles, I prefer non-US/UK media in my own language. Torrents are pretty flexible on this front. Sure you need to know what you are doing, but if you know what usenet is, that means you can figure it out.