Sure, but throw in a dependent or two (or five) and see how quickly the math changes.

2020 MFJ w/3 kids = $7,000 EIP split $3,500 TP and $3,500 SP because that's what the law says.

TP files 2021 MFS w/3 kids, gets $5,600 - $3,500 = $2,100 RRC.

SP files 2021 MFS w/0 kids pays back $1,400 - $3,500 = $0 because nobody has to pay anything back.