The insinuation is that lobbying is bribery (and on the more egregious end of the spectrum, it is). In countries where lobbying isn't legal, it would at least help much less.

I think the idea is that if lobbying is legal, then it is regulated and thus how much it can help is limited. In countries where lobbying is illegal, it can take a form of bribery and then you can (potentially) achieve a bit more in this 'unregulated-bribe-anyone' space...

That's an odd argument. If the goal is not to have your politicians be bought and paid for, then surely making it legal to buy them is arse backwards.