depends what you mean by "discovery", I think. Seeing a nova or supernova or comet before anyone else is more a product of chance than equipment, coupled with a painstaking commitment to surveying - which is largely automated and professional these days anyway.
On the other hand, Seestars and their users certainly contribute to campaigns e.g. the current BAA one on variable nebulae, or various variable star ones, and that's where many discoveries are made - it's just not by a single scope or user on a single night.
Meteor science has been transformed in recent years by the introduction of (relatively) cheap video systems, often run by amateurs, that combine results in near real-time: the relative inaccuracy of those systems is mitigated by having many more measurements than was ever possible before: to the point where scientists are often collecting meteorites within a few hours of a fall: very much cheaper and quicker than asteroid return missions. And the precision with which radiants and orbits are known has increased massively. The real breakthrough was finding ways to pool and analyse massive amounts of data and having common means of collecting and measuring it, alongside mutual support and easy access to get people involved.
I'd really like to see similar approaches to "citizen science" with Seestars and other smart scopes. It's not the instrument, but how you use it to collect data on objects of interest, how you involve and collect that data from lots of people and how you apply statistical techniques to refine and analyse it. There are lots of discoveries waiting to be made, but very few of them will be a "eureka" moment from a single amateur using a seestar.