Aside from being a plot point, this concept makes no sense (to me). A warp bubble's relative velocity through space is only limited by the amount of power you can throw into it. Theoretically, it has no limit.
Yes, that's exactly the point. "Warp 10" is just a really crappy name for infinite speed, which is, by definition, the absence of a limit. It's misleading sticking a finite number on an infinite value, and it's done nothing but create confusion for the past 30 years.
The thing is, when TNG started, Roddenberry wanted to impose a limit on starship speeds for dramatic reasons, since limits on your characters' power are generally a good thing to have. So he arbitrarily decided that warp 10 would be the fastest a ship could go, even though there had been references of warp factors up to 13-plus in TOS (and warp 36 in TAS, though in a really stupid episode that's generally best ignored). At first, it was assumed to be a finite value, hence Geordi's line "We're passing warp 10" in "Where No One Has Gone Before." But somewhere along the line, it was decided to redefine it as infinite velocity -- keeping the name "warp 10" as a sop to Roddenberry, but abandoning the concept that it represented any kind of actual speed limit. So from warp 1-9, the velocity equalled the speed of light times the warp factor to the power of 10/3 (theoretically, according to the published charts, although the onscreen speeds were almost always much faster than the charts alleged), but beyond that, it was an asymptotic curve with the velocity increasing to infinity as the warp factor approached 10. So instead of sensibly increasing the warp factor, you were stuck with doing things like warp 9.9, warp 9.999, warp 9.9999999, etc. It didn't represent any actual limit on speed, just an arbitrary unwillingness to use a number higher than 10.
The
TNG Tech Manual struggled to rationalize this by asserting that there were nine velocities at which the interacting fields of the warp bubble stabilized in a way that reduced the power utilization, making it easier to travel at those effective speeds than at intermediate ones, and these were the integral warp factors 1 through 9. But there was no such stable configuration between warp 9 and infinite speed, and thus infinite speed was named "warp 10." Which is really contrived and confusing.