To nitpick, we don't know that anything shown in "Descent" would be available to the Collective. It could all have been the doing of the separated group of Borg - the ones who adopted fast Drone movement, ranged personal combat weapons and freedom of emotions, among other atypical features.
When we do see Borg transwarp in action, much later, the VFX is somewhat different, supporting the idea that Lore's Borg used something unique. Merely a development of standard Borg transwarp, or something else altogether, dug from deep in the Collective memory or adopted from Lore's infinite resources of wisdom? Hard to tell.
It's a more general point that the Borg don't seem to evolve on timescales as short as centuries or millennia. If they have transwarp today, they probably had it three thousand years ago already. If they weren't
stable like that, how come they have existed for hundreds of millennia yet not skyrocketed to some sort of a more prominent existence, through a dozen "singularities"?
Voy "Hope and fear" - we saw a species that survived the borg for centuries before being defeated.
And we never learned they would have been any more powerful than the UFP, in absolute terms.
It instead rather seems that the Borg don't care all that much about anybody
, not in the sense of seeing them as threats needing to be eliminated. The Borg are invulnerable to counterattacks, and have no pressing need to cause devastation. They can assimilate on a very prolonged schedule - the slower, the better, because that gives the opponent more time to invent cool countermeasures that then fall in Borg hands.
We see how "underwhelming" attacks are deliberately used to promote development in victims in "Child's Play". Sending individual Cubes against the UFP is quite probably just the same thing on an ever-so-slightly larger scale.
It's probably noteworthy that "Best of Both Worlds" is the only time the Borg claim they have come to assimilate Earth, or the UFP, or whatever. Also interestingly, they do so through Locutus, not through their Collective voice. It's as if they needed the services of a dedicated liar to get their act going...
You will have the right to say this when you will actually present evidence of your own
Naah. You better just learn some manners, then learn the meaning of those words, and then return to the conversation. No action is required from the part of anybody else.