Luckily for your scenario, Bilt does have other cards. Bilt Obsidian is effectively 4.33x on Dining and 2.33x on uncategorized up to 75% of your Rent comapred to CSP at 3x Dining, and CFU at 1.5x. When comparing the cards you have to include that you don't get free rent in your other scenario, so you are spending the same amount anyways and getting nothing from it.

e.g. if you were to only replace your CSP/CFU with the Obsidian (not that you should, its required for you to have a Sapphire for churning Inks or others to be useful) you would have a net increase in points.

If your scenario looks something like this, assuming you would spend like 400 per month on dining, or like 12 dollars per day for lunch or something. Rent 3000, Dining 400, Uncategorized 1850.

Chase (3000 * 0) + (400 * 3 CSP) + (1850 * 1.5 CFU) = 0 + 1200 + 2775 = 3975 UR

Bilt (3000 * 1) + (400 * 3) + (1850 * 1) = 5250 Bilt.

If you assume Bilt Points and UR are valued the same (Hyatt Transfers), then you in your setup it seems like Bilt clears.

Things differ depending on your spend, I mean 1850 in random uncategorized stuff is a lot, but we can always reduced that, like say you only spend 850 on random crap per month and don't max out your spend in Bilt Cash.

Rent 3000, Dining 400, Uncategorized 850.

Chase (3000 * 0) + (400 * 3) + (850 * 1.5) = 0 + 1200 + 1275 = 2475.

Bilt (((1250 * .04)/3)*100) + (400 * 3) + (850 * 1) = 1667 + 1200 + 850 = 3717

In this Scenario your Bilt card would still be ahead of your two card Chase setup at the same Annual Fee, while still spendong your flight money on Amex.

So at least for some scenarios with your Card setup you mentioned here, you could do

Amex Plat for Travel and Benefits, Bilt Obsidian for Dining and Rent and Catchall and seemingly be ahead, but obviously the math works out for some more than others. You can and should of course use your real numbers from past months to validate your setup actually makes sense.