I know this kind of misses the point, but Factorio is one of the most addictive and rewarding gaming experience I've had. Beware: within months it ate up collectively hundreds of hours from myself and members of my friend group.
It definitely scratches that Factorio itch but in a different way.
Roadmap includes a ton of interesting things which should make it more challenging in the long run.
Further, how was launching your first rocket anything other than rewarding?
With all of that said though, getting to a result is always a great feeling and basically why I still play it after all of these years.
Launching the rocket was inevitable after a certain point, it was just a matter of tuning everything well enough to get there as quickly as possible, which seemed always to be hampered by some tedious task or another. Having robotics much much earlier in the game might have helped a lot there.
You were watching a speed runner who knew exactly what they were doing. I was a first time player who didn't. I spent north of 30 hours tediously laying out factory bits and wondering "why the hell can't I automate this?"
P.S.: and hey wait, whole speed runs of Factorio seem to be in the range of 2-3 hours, and you're suggesting under 2 hours isn't late game?
But robotics itself only requires blue research. In my own speed run of ~6h40m (admittedly, on an older version of the game, but the game pre-blue science hasn't changed much), I got blue science in about 2h, and bee-lining for robotics after that would only take a couple of researches beyond that (advanced oil, electric engine, robotics, and then construction robotics to do anything useful IIRC).
I wouldn't call anything that takes only blue science to get to be late game; for me, that requires at least purple or yellow science. Robotics is on the other side of the oil barrier, which is definitely going to push it far later in the game for new people, but it's also accessible before you hit the point of needing to repetitively scale up your factory (which tends to come with purple/yellow science), so it is accessible before you really need it. However, the game doesn't particularly guide you towards knowing that it exists, so I can see how it might be frustrating for new players.
IIRC, Factorio does have a sandbox mode where you can just create arbitrary designs without having to gather/assemble the stuff first.
I will note that someone who does enjoy the game would never describe themselves as having "finished" it, there is always more to expand, more to optimize, etc. Not to mention all the mods to explore!