They would likely work in a similar way, being susceptible to the same tactics.
Imho, the main problem is that there's no deterrent. Even if you get caught doing some very black hat stuff, worst thing that can happen is to get a manual penalty. Remove the outlawed stuff, wait a month or two, submit a reinclusion request and you're back in business. If it was a "once you're caught, you're out for good" thing, SEOs would tread much more carefully.
I disagree that they'd work the same way because Google has invested millions of person-hours into a proprietary algorithm that they share with no one.
DDG and Bing often have wildly differing results for me.
That's true, but I believe that they'd arrive at similar techniques if they were rivaling Google. Today, it's a Cyborg-Behemoth vs a few scrap-yard tinkerers. If Bing & DDG had the budget and manpower Google has, the results would probably become more similar - but who knows, there might be completely different approaches to search that we just haven't seen.
In any case, we probably do agree that it would be very good in general if there was more competition in the search market.
Imho, the main problem is that there's no deterrent. Even if you get caught doing some very black hat stuff, worst thing that can happen is to get a manual penalty. Remove the outlawed stuff, wait a month or two, submit a reinclusion request and you're back in business. If it was a "once you're caught, you're out for good" thing, SEOs would tread much more carefully.