I agree, though not every explorer will see it that way. Some will see it as "What's the point heading into the black if I'm gonna see starports everywhere?"
Same thing was said for Carriers. And yet here we are, billions of systems without carriers in them.
If you never want to see a populated system, can filter them out and set that filter for jumps and you never have to ever see a populated system, even in the bubble.
So I think that's a pretty wild overestimate of how many people are going to just endlessly colonise systems. Some will surely keep doing so, as a group effort. Some will carve out a little spot of their own, some will never engage with the mechanics at all.
As an explorer who also has spent some time out in the black, I also see it as a non-issue. I have trivial ways to avoid population centres and the sheer scale of the universe is going to see it remain mostly empty pretty much regardless of colonisation. Only have to look at the percentage of discovered systems vs galaxy size to clock on to that.
Frontier has also solved that to an extent by requiring an anchor system. 10ly just makes expansion an intractably pointless exercise, and the moment Frontier plonks down a hand crafted system in the middle of nowhere again, more or less invalidates anything cmdrs might do.
Having some sort of limit is sensible just from a logistics perspective, but 10ly is very conservative, even for Frontier.
I think folks are wildly overestimating how much of an impact colonisation is going to have and aren't really looking at the bigger picture.