In the distant past I was given a year off from my job, as I was intolerably stressed out. At the end of that year, I simply never went back to the job. Ever since then, I've felt hugely relieved that I never had to go through the 'Leaver's Presentation' business, the thank-yous and goodbyes etc. I watched people doing that sort of thing for years, never understood how they could do it, and dreaded ever having to experience it.
I've also had the same experiences as others on this thread at social events. I once sat for about two hours with three people I didn't know and didn't like, after everyone else had left, simply because I didn't know how to 'take my leave' earlier.