There are many open source communities that provide good and effective tools and ecosystems for their users. In fact, there is not doubt that the best programming tools available in this age, follow a pattern of a core open source software system that provides the essential functionalities, and a plethora of open source modules and extensions to the core module, so that the end developers can easily tailor their solution to their specific needs.
In almost all cases this works perfectly, with well maintained extensions that are open source and free for everybody to use and extend. For example, I have never seen a closed source or paywalled module for Python, npm. Ruby on Rails, for Java, all the modules needed to make your application work are there to be used.
But there are some specific open source communities, where eventhough there is an open source core module, it is practically unusable unless the user buys a plethora of closed-source extensions. I call these communities "Open Source In Name Only" (OSINO), since their objective seems to be to lure foolish developers into thinking that the ecosystem is open, while in reality it is impossible to use the software even for the most basic use-cases, unless you either spend hundreds of dollars in extensions, or spend hundreds of hours implementing all the missing functionally over undocumented source code. Some notorious examples are Wordpress, where you can't even have two languages in your website, or prestashop, where you have to buy extensions even for basic tasks such as accepting credit cards, or for allowing the user to edit his order while it is in the checkout cart.
A common pattern for these communities is to make it as difficult as possible to determine beforehand if a module is free or not, using shady tactics like not allowing to search by the cost, not disclosing all anti-features that the "open" version of the module provides, etc. To give an example of this, there was a wordpress theme that was "free", but you had to buy the premium version if you wanted it to scale on mobile.
My question is how can an open source community protect itself from devolving into a OSINO? Is there anything that either the core developers, or the community around the software can do to prevent such practices in their ecosystem? What defence do the developers or the end-users in open source communities have in order to in order to protect their community from this, and how have some communities managed to achieve this while others have not? And how can an end-user easily determine that the software they intend to use is really open or an OSINO?