If a producer relies on a specific synth or effect that is considered "abandonware" (software no longer updated by the developer), a new FL update can render that plugin useless. To keep using their favorite tools, producers must remain on the older FL build that supports them.
This means that using an older version of FL Studio is usually a choice , not a financial penalty. If you bought FL Studio 20 years ago, you still have access to FL Studio 21 today. fl studio older versions