This is addressed in the article, if you license your software as MIT, whoever uses it is in their right to do essentially whatever they want with it, including using it for profit without paying you a dime.
The idea with dual licensing with GPL is that the user has to either open-source their code, which most corporations will not want to do, or use the paid licensing scheme.
> The idea with dual licensing with GPL is that the user has to either open-source their code, which most corporations will not want to do, or use the paid licensing scheme.
That's part of it (and it's probably dominant when the software is infrastructural and typically has other software built on top of it), but not quite the whole story.
The other part is for software that is more of an application than a component: when your commercial version has additional features aimed at deep-pocketed customers (typically "enterprise" features like SSO, or various forms of compliance). Since these features aren't released as open source, you are the sole source of those capabilities. Someone else could duplicate those features and release them as GPL, competing against you with a completely open source offering, and nuke your profit margin, but what they can't do is duplicate the features and keep them proprietary as you are doing. So anything they release like that is now effectively free, and they don't really get any of the attractive profit margins you had, making it harder for them to recoup the sunk cost of duplicating those features.
IOW, they can fill in your moat, but then can't really dig their own.
This gets back to why big companies release software as open source: Sometimes they aren't just trying to commoditize their own complements, they are trying to commoditize someone else's core to blow their business model up (or more accurately, cause their competitor's market to evolve faster than they are prepared for). Open Source isn't the only possible play here though. A free or freemium offering as well as other tactics can have a similar effect.
Certain companies have complained because other companies made a profit from selling hosting of their (A)GPL software.
This is totally OK with the (A)GPL which is why certain companies has tried to come up with new licenses, none of which are compatible with OSI Open Source.
(I specify OSI Open Source here since someone took the time to dig out enough references to convince me (and probably others) that the term open source was used more or less for the same idea well before OSI started using it.)
The idea with dual licensing with GPL is that the user has to either open-source their code, which most corporations will not want to do, or use the paid licensing scheme.