Unless I missed a part, I think one big change you're missing is that the capture time got cut in half in an update right after s6 LAN. If I remember right, 1x on the point used to be 24 seconds, and then got changed to 12 seconds. Eveb with quite a few bodies on point, it still took a very long time for a team to capture prior to the update. Because of this, I think "old Viaduct" should be considered s5 to s6.
This changed entirely how Viaduct was played, because back on Pandemic / blight-fanom, our strategy was to keep TLR and I in house. Justin ran sniper and everyone played mostly passive, maybe except ww going in to annoy the other team. Justin did a fantastic job at constantly rotating sniper spots to pick people off, too. Once the other team started to throw a ton of bodies on the point to start the ridiculously slow cap, then TLR and I would walk out of house and uber onto the point. Our entire team would collapse on them while Justin continued to snipe people.
In s5, we tried to make this work and did an okay job of it, but we were still a new team. In s6, I had no doubt in my mind that we were the best team in the world at it. I think that's because Ruwin was also incredible at roaming around as scout and getting important kills, along with Orzo just being a ridiculously solid Demo. I always felt like we played the map to near perfection in s6.
In s7, not only did we have a lot of roster changes, but we couldn't play Viaduct the same anymore after the changes. Staying in house was no longer a good idea, because you wouldn't get to the point in time if they threw a bunch of bodies onto point. You *might* get there in time, but it would be 95% capped, which isn't really worth it at that point. It's probably better to let them cap it, fight, and if you die, you get quicker respawns. But ideally, you need to play closer to point to stop them from getting a bunch of cap time.
None of this was an issue prior to s7, because by the time you would exit house to uber onto point, the point might have been capped somewhere around 25-50%, which wasn't a big deal. Also, running 24/7 sniper wasn't nearly as good as it was before, and playing more aggressively (such as forward holding) tended to be more rewarding.