I believe strongly so, however companies doesn't like this, hence the current state we're in. Also it's part of the "advertising" done by the companies.
replyLast but not the least, many people are very ill-informed about GPL and how it works. I experience this when we discuss this with peers.
This is why I only use copyleft (or non-commercial/share-alike) licenses on what I build/produce/put out.
If you share your code with me under a copy left license, I will share my contributions under the same copy left license... you will not then be free to ask for money for things built on top of or with my contributions. You may be okay with that, but it is a decision you have to make.
replyA common misunderstanding with the GPL and other copy left licences is that they care about money and monetary transactions.
replyThey mostly do not.
They only demand that you offer the source code to anyone that asks for it if you also distribute any kind of executable (you may even charge to cover the costs of the distribution).
The AGPL expands this to SaaS's too to close that loophole.