I totally get the rants about the statement, "Sit with your feelings." Although I now feel that I have a much better understanding of the statement and how to do it, I still hate it because it sounds so simplistic. When I was tumbling around and being swamped with my feelings, I didn't find the statement in the least helpful.
BUT I will admit that over time, I've learned to understand it and use it

I agree with feralkittymom's description of there being a difference between sitting with feelings and dwelling or stewing in them. I know that when I used to journal, I would rant and rave and throw hurtful arrows at myself. It wasn't in the least helpful and indeed made me feel worse.
What changed for me was finding a way to recognize when strong emotions were swamping me and dragging me under--truly like a strong undertow, dragging me under and making me feel as though I was about to drown in a sea of stinging jelly fish or being eaten alive by man-eating sharks. I taught myself that those feelings truly don't last forever (even though it felt like they did) if I would just pause a moment and turn a curious ear toward them. It wasn't about piling on more abuse and rants against myself while "sitting with them", but it was about being truly and openly honest about what triggered such strong hateful thoughts. It actually started with using words like: "Hey there! There are those thoughts about being a stupid a#* are back. Where the heck does that come from? What's happened or what was I doing right before they came and parked themselves in my brain? When was the last time I felt like that? Is there a similar theme? Is what the voice saying really true (tricky one because I used to fall right into agreeing with the voice) What things have I done that show that isn't true about me?" <<--this may sound trite and silly, but I really had to drastically change how I talked to myself. I'm usually a pretty harsh and hurtful person when having a dialogue inside my head, so I had to make a complete 180 to be softer and more
curious about what was happening. It takes practice but the good thing is that I'm the one who is making the changes. I'm not relying on someone else to validate me or bring me out of my funk.
I'm not saying it works all the time, but it sure has resulted in some changes that are bringing me a bit more peace. Can't shut the voices off totally, but softening them and being curious about them has lead to some real growth. Just wish therapists would quit using the stupid "just sit with your feelings".