I can see why they nerf the EMP and tweaked Revenant's totem, because it started to get annoying with the help of Wraith and Revenant to easily push enemies squads by making them weaker and silenced.
Now that the EMP slows your teammates, people are not going to be happy about us (specially the randoms), because if your team and the enemy squad are close, it could help my squad by making the enemy squad weaker, or I ended helping the enemy squad by making my teammates an easy target if they are in the open without taking cover because I slow them.
Which means that using the EMP now requires timing and positioning so I can't disrupt my teammates.
Also they fixed an issue where the EMP couldn't destroy Loba's Black Market.
Source: https://www.ea.com/games/apex-legends/news/season-6-patch-notes
In the patch notes the store rotation throughout the event was shown. Octane, Pathfinder, Wattson, Caustic, the r-301, r-99, spitfire, and hemlok came back from SO
Yes. They made that change in season 4 ranked:
"Mirage's Decoy Trigger, Crypto's EMP and Pathfinder's Grapple now give assist credit for the standard 7.5s after activation, even if they deal no damage."
The only difference between season 4 ranked and season 8 ranked is the assist timer is now 10 seconds instead of 7.5 seconds.