Ultimately most things in life and society where one freely gives (and open source could be said to be one such activity) is also balanced by advising everyone participating in the "system" to also reciprocate the same, without which it becomes an exploitative relationship. Examples of such sayings can be found in most major world religions, but a non-religious explanation of the dynamics at hand follows below.

If running an open source model means that I have only given out without receiving anything, there remains the possibility of being exploited. This dynamic has always existed, such as companies using a project and sending in vulnerability reports and the like but not offering to help, and instead demanding, often quite rudely.

In the past working with such extractive contributors may have been balanced with other benefits such as growing exposure leading to professional opportunities, or being able to sell hosted versions, consulting services and paid features, which would have helped the maintainer of the open source project pay off their bills and get ahead in life.

However with the rise of LLMs, it both facilitates usage of the open source tools without getting a chance to direct their attention towards these paid services, nor allows the maintainer to have direct exposure to their contributors. It also indirectly violates the spirit of said open source licenses, as LLMs can spit out the knowledge contained in these codebases at a scale that humans cannot, thus allowing people to bypass the license and create their own versions of the tools, which are themselves not open source despite deriving their knowledge from such data.

Ultimately we don't need to debate about this; if open source remains a viable model in the age of LLMs, people will continue to do it regardless of whether we agree or disagree regarding topics such as this; on the other hand, if people are not rewarded in any way we will only be left with LLM generated codebases that anyone could have produced, leaving all the interesting software development to happen behind closed doors in companies.