[varispeed]

My point is that there are many developers who would love to contribute to open source projects, but they don't have wealthy parents who pay bills, didn't inherit a flat, have families to feed and so on, so for them only viable option is to seek employment or work on their own business. People who can commit their time to work on open source are privileged and by giving their work away for free they create a situation that there is less work for people who cannot afford that. For example a company instead of hiring developers, paying salaries and taxes to create a tool they need, will instead use open source project for free and that means other developers are missing out. Ensuring that everyone gets paid levels the playing field. This is the same situation as you have with free internships - there are people whose families have money, so they can afford to get experience working for a company for free and that puts people from poor background into a disadvantage - that's why in many places unpaid internships are illegal.