I think some of those things are true-in certain types of poly.
For me-I have two relationships, but they are both live in partners, we have a family together. We have children and grandchildren. We've all lived together for 10 years. I've had a relationship with one for 15 years, the other 20 years. I don't see an end in sight for either.
But-I don't consistently date. I love two men. I don't believe in seeking partners-I never have. So, I don't date. I do socialize and meet new people and there is always the possibility that another person will enter my life and I will fall madly in love with them also. But I'm not looking for that.
Also, I don't add responsibilities to my life that I don't have time to focus on. So, a new partner couldn't be a secondary. I can't promise even 1 night a month away from my family outside of school. The only way another partner would be feasible for me was if it was someone who was willing to be a part of my current family life. Because for me to want to be in a romantic relationship with someone, I need to know I'm going to be able to see them and spend time with them on a regular basis-and in order for me to spend time with ANYONE-even friends on a regular basis at this point in my life-they have to be willing to spend that time shared with family..
I don't have time right now to continue. But I do think you bring up some great points of consideration and potential discussion! I will check back in after classes tomorrow.