No. Claiming this underplays how appalling Stalin was. Lenin purging Mensheviks AFAIK, meant losing party membership and maybe emigrating to continue your political project, whereas Stalin's Great Purge killed a million people. This isn't a defence of Lenin, it's just that Stalin was on a different level entirely.
> Their biggest effect was external: most welfare systems were started in the West in response to the observation that it was a bad look for capitalism
What? That's nonsense.