Originally Posted by GeneralAntilles

It's a large part of it, sure, but it's definitely not the only part, and the world isn't as black and white as you seem to think it is.

Open core is a game on rather than a valid expression of software freedom, because it does not cultivate software freedom for the software user. In an open core business, there is a core package which is open source and which delivers basic functions. That package can be used freely under the terms of an open source licence, and there's no issue involved at this point - as Lampitt asserts,

"the customers enjoy, in a way, guarantee of liberty from the vendor; if things go sideways for the vendor, there is a sort of a "guaranteed escrow" of the source code."

But to use the package effectively in production, a business probably won't find the functions of the core package sufficient, even in the (usual) case of the core package being highly capable. They will find the core package largely ineffective without certain "extras", and these are only available in the "Enterprise Version" of the package - which is not open source.

To use those features, you are forced to be a customer only of the sponsoring company. There's no alternative, no way to do it yourself if the value delivered doesn't justify the expense involved or if you are time-rich and cash-poor. Worse, using the package locks you in to the supplier. If they prove a bad choice as a supplier, or if your business needs change, you have no real choice beyond "take it or leave it". In many cases, ending your subscription with the supplier will mean losing your rights to use the Enterprise Version all together.