The reason YPYT is a thing where people get upset if the tank or whoever slows progress is because it is generally accepted that time is valuable. In both situations where one or more players try to force the pace of a run to their liking, one being faster and the other being slower, the most impactful is the one going slower just because you are wasting other people's time. Especially now that there is an option for every single duty where you can take it at your own pace and not impact another person with the Trust system. Now, if people communicate like grown human beings instead of entitled children, there should be no problem at all. I had a healer ask me to go slowly because they're rusty with healing. I had no problem going slow and none of the dps pulled ahead because the healer used their words. After a few pulls I asked if they were back in the groove and if we can speed up and they agreed. Everything went super smoothly after that.

If you want to go slow or at your own RP pace, please don't inflict that on others and use the Trust system. If you need some time or special consideration with a group of players, communicate that but be mindful that you will also be affecting 3 other real life humans with their own thing going on. You aren't the center of the universe any more than they are.