I'm not sure, but I think the logic for the latter is that by sending a straight limit order, you would consistently be moving the bid price up by continuing to

I'm not sure, but I think the logic for the latter is that by sending a straight limit order, you would consistently be moving the bid price up by continuing to fill the highest priced bid or filling the highest priced ask, up to the limit. Of course, this would be true even if there were no algo trading... so... I dunno! Oh, it's also worth noting that this is not an issue for the individual investor because most individuals buy stocks in very small blocks, usually less than the minimum increment size that shares trade at on the open exchanges. Larger, institutional investors use algorithms from their trading partners. I guess if you're a millionaire personal investor you're SOL though. But usually people with that much money have a Wealth Management firm to take care of their trading for them.