i agree with the idea of similarities between Steptoe and Only Fools, they're actually quite glaring when you think about it.
Rodney is sort of like Harold in certain aspects insofar as his wanting to break away from Del and Del being of the "what would you've been?" mentality towards him. Loads of stuff is similar to Steptoe. There are even certain episodes that are like, a take off from Steptoe.
The Lead Man Cometh, the concept of nicking lead from the roof is taken by OFAH in that episode where Del witnesses a miracle where that statue of the virgin mary starts crying when he only went to church to confess to having bought nicked lead cuz he felt guilty and it turns out the lead he bought was nicked from the church roof.
Robbery With Violence, the 4 skinheads and a pakistani motif is used in only fools and horses where grandad lies about being mugged and keeps changing his story to "i tried to stop em del but there was 5 of em" which then turns to 6, which then turns to 7.
There's quite a few others but they aren't immediately apparent to me, i'm an old man 'arold, me memory ain't what it was
It's not quite plaguarism but it's clear one is a take off from the other, that much is undeniable.
And also just as a general thing, John Sullivan, the writer of Only Fools openly admits in The Making of Only Fools and Horses that he first got his idea that he could or should try writing after watching The Offer because of the mixing of pathos/tragedy and comedy.
They say the highest order of art is that which walks the line between tragedy and comedy, Steptoe is positively Shakespearian in that regard, to my mind it is the absolute peak of British comedy, quite frankly it's theatre to me and i appreciate and understand it on that level. It has everything, human relationships, politics, social satire, side splitting comedy and...God, it's just beyond words really, i could never ever tire of it and i've been watching it since i was a kid and i truly feel blessed that my introduction to comedy, the benchmark from which i measure such things comes from such a high watermark.