I remember the good ol' days way back when...the "BullWorker" was fashionable...everybody had one. hastily looked like a small bogostick,

Then came the pulleyset parenthetically attached to the door knob. Once gotten hit in the noggin when I forgot to latch the lock on the damn door...
Anyways..the moral is...if it works for ya,,use it by all means...but you will outgrow it because the body gets used to restricted movement, like bowflex, etc
Free weights, which help build tendon strtength,,,is what's most useful in cowardly lifting things _heavy_
Good luck in your iron or cable endaevors