I think there's some clarification that may help here:
1) P1 or P2 mode doesn't necessarily refer to being single or not. There are many folks in 1 player mode because they have an unwilling spouse so I wouldn't use P1 in this instance but rather say
The CP may not make sense for a single person.
2) You could also be in 2 player mode and have a CP not make sense. Your spouse, mom, etc. may let you apply for cards in their name but not be a regular travel companion so I would also say that
CP also may not make sense for a person in 2 player mode
3) I would disagree with the statement that it's better to get UR cards and transfer them to SW. If your goal is to get SW points, then get SW cards. At times you can get 50k or even 60k RR points for just $2k spend. There is NO UR earning card that offers that amount of points for that little spend (CIC/CIU = 50k for $3k; CSR/CSP = 50k for $4k; CIP = 80k for $5k).
4) The CP is a fantastic benefit, BUT for a family of 4 the value of the points probably is as important or even more important than the value of the CP. 124,000 SW points get's me over $1,800 in flights! That value alone is amazing, now if I can use the CP to save some of my points on a few trips, even better
5) Also it's worth pointing out that you can cash SW points out via some gift cards (including Target and Walmart) at $0.01 each if you have the CC so a Southwest card can even make sense for somebody who has no interest in flying Southwest.
Hopefully these are some helpful comments