I thought some were very tight, so some users didn't manage to plug it completely in.
The issue with that, is that if you actually apply reasonable force, and it didn't click home, it would still be tightly in place, due to friction. The issue shown on melted connectors is that they were not tightly pushed in at all, but very loose.
Once the issue was known, and people were being careful I don't think I've seen a case, where people couldn't seat the connector.
IMO, tight connector played a part, but it's mainly people not paying adequate attention. Which is rampant on any DIY stuff done. There is YT channel called "Just Rolled In" where car mechanics show what came into their shop and people's DIY on their cars just blows my mind...
If you are aware and paying attention, it's a complete non issue.
I'm sure there have been plenty of inadequately seated 8 pins out there as well, but they don't have as much current density to cause issues, but when dealing with 450 Watts+ in one connector, paying adequate attention is a must.
Back around to the 3090 Ti. It's the exact same connector. If careless it's susceptible to the same issues. But that wouldn't be my reason to avoid it.
I'd Avoid the 3090 Ti because of obscene power requirements, even higher than the 4090.