Ok. I'm not specifically familiar with either of those resorts. Are you referring to Punta Cana Princess All Suites, by any chance? That one, I did stay at solo.
On one of my solo trips, I had made some contacts here on TA beforehand, and did meet those individuals at the resort (PCP). For my second solo trip, I hadn't prearranged to meet up with anyone at the resort, but ended up meeting a great group of people (we were all meeting for the first time.... couples, singles, friends, families), and ended up spending most days and evenings together in some fashion.
I would say it's easy to stay by yourself just as it's easy to meet folks, depending on what you want out of your vacation.