I mean the actual medicine part. When I think about it, there are still no cures for the major things that ail us (e.g. cancer, etc.). China cured that one guy from his diabetes, but I haven't heard anything beyond that.
The "promise" of stem cell technology from 20 years ago still hasn't amounted to anything that your average person can get (and there are all sorts of shady overseas places that give ppl "stem cell" injections, but honestly we should have figured out that shit by now).
If you tear a ligament/tendon, guess what, that shit will never heal back to 100%, and the "oh just rest and do physical therapy" shit is annoying because you're only really working around the problem and not solving it.
On top of that, as you get older it's harder for your body to heal from injuries, sickness, etc. and I've yet to see any legit progress on anti-aging. If your heart is damaged or arteries clogged, I don't see any way to reverse it.
And after covid, it's all been fucked. How many people have long covid and the medical establishment just throws it's hands up 
basically treating an entire segment of the population as though it was a bad crop yield ("I guess there's always the next batch!!).
And doctors themselves are often the biggest dipshits out there. They are high off their own supply because they're "smart" and lack the empathy to actually listen to patients. Either they're older conservative types or younger lib dipshits. And there are so many horror stories about nurses that talk shit about patients. It's just dismal.
The common reply is that "biology is hard" but honestly that's a WEAK excuse. So many advances were made in the past, and there are so many more to be made. An actual concerted international effort, unhindered by profit motives and fucking insurance, hospital, pharmaceutical industries, etc. would almost certainly yield results. I mean look at Cuba coming up with a lung cancer vaccine and curing HIV in an infant. Look at China curing diabetes in that one guy. These advances are possible, but honestly they aren't coming fast enough. If you're suffering from a terrible disease/ailment, the "promise" of a new drug that still may be 10 years away is just terrible.
So even if we had 100% socialism now with free healthcare, there are still so many things that need to be addressed. I can't help but think that had the Soviet Union not fallen, we would have had cures for many things. Hopefully 
can do something about this, but overall I'm still super bummed that the future we dreamed has not materialized.
in addition to capitalism and imperialist wars holding society back, technology is not like a linear video game progression, everything is subject to the law of diminishing returns. we have already made all (or most) of the easy discoveries, most that are left are very difficult or impossible or particularly power/resource-intensive. some stuff might just be exceptionally inimical to our current thought paradigms and material conditions though. for example Rome probably could have built steam engines, they knew of the technology from toy/model examples from greece, and they eventually had better metallurgy, but slaves were overall cheaper and more important to the economy and in fact rome enacted laws against certain kinds of labor saving devices/factory designs (yes they had slave-powered factories in ancient rome) to protect the economic position of slavery. it will be even more crucial to efficiently organize production and resource allocation the 'farther along' we go. unlikely we could ever build a dyson swarm etc. if we are wasting resources on imperialist wars and long-term-inefficient economic scams and total environmental destruction.
Yeah but hasn't the history of scientific progress shown that every time we think we're at a stagnation point, a breakthrough discovery is made that shatters the old paradigm?
Yes, because countless numbers of people make it their life's work to advance our knowledge, and their work would be impossible without the discoveries of the people before them.