Current winning bid and max bids are two different things.
Incremental bids are a loser's strategy. As in, the only way you win making incremental bids is if there's no competition. But, assuming there is competition:
If your script was to do that, take the current max bid + the bid increment in the final milliseconds, you'd lose because the current winning bid is overwhelmingly likely not the max bid of that bidder, an incremental bid won't beat him.
If your script was set to make a continuous series of incremental bids until it is the highest bidder, that's really risky, you could end up way overpaying. I know a guy who's sniped bids for $30K for items that went for around $5K. Can you imagine having your script win an auction for you at 6X what it's worth, especially a high-dollar item? No, there needs to be a cap to it, a maximum bid amount where the script stops. And if you have a maximum bid, there's no need for a script, you can accomplish that with a single manual snipe bid and let eBay's SW handle the incremental part.
The advantage to snipe bidding software / scripts is you don't have to be online and active to place the bid at the time of the auction end. But otherwise there's no competitive advantage.
And really, cutting it down to the final milliseconds risks missing out placing a bid in time due to network latency issues.
Thanks for clarification - makes sense. I don't bid eBay much, at least competitively.