Why waste a 5/24 slot with no SUB? You're going to spend on a 1x card?
A few points
1) I've neglected my game for quite a few years, I don't see myself hitting 5/24
2) They do have a hidden SUB
3) some transfer partners are not available with amex and chase, these may offer significant mileage savings
4) They have some crazy monthly offers like bonuses of 75-150% on transfers (not every month)
5) Rent day gives you 2x on all expenses of the day (2pts for all spend, 4pts for travel, 6pts dining. UpTo 10k bonus points per month)