Sure, that version of events requires way more people in on the scam and would leave behind way more evidence, which hasn't turned up, but I can't prove it didn't happen so it's still totally worth investigating further.
GBI hand checked a random sample of 15K ballots in Cobb county for signature mismatch issues and found no fraudulent ballots, but that apparently doesn't count for anything, because they didn't look at Fulton county which is now where we're saying the fraud was. Cobb county still probably cheated the election since Biden won there, but they must've just forged the signatures too well.
And you like to pretend all you want is more election security and verifiability. Well gee, I'd like that too, as long as it doesn't compromise the secrecy of the ballot or the accessibility of voting to eligible voters. I think all software used in elections should be open source, for example. But there is a massive gulf between wanting better voting technology, and claiming that an election WAS stolen. The latter requires serious evidence. We do have some ways of verifying the election such as checking the paper trail, and when we've done that here, fraud hasn't shown up.
You'll always claim the investigation is insufficient unless it does find fraud, and completely discount the value of anything that confirms the count was correct. Yet you'll give credence to a "forensic report" from batshit crazy Russell Ramsland (mixed up MN and MI, claimed 781% turnout, claimed fractional vote counting based on rounded percentage numbers from NYT...)
Why is it so easy to believe that hundreds of poll workers, election officials, judges, governors, secretaries of state, etc. conspired to commit or cover up fraud, and are all lying about it - but hard to believe that Trump and his allies are the ones lying? Either way somebody is lying. And there are multiple occasions where I KNOW Giuliani said something that was complete BS -- such as that the number of mail-in ballots returned in PA exceeded the number requested. So it really wouldn't shock me at all to find out more, or all, of what he said was garbage.
The bar set by the "stop the steal" crowd was that unless you uncovered that Donald Trump really won the election, you didn't investigate hard enough.