I find your reasoning very strange, if anything, GPL ensures that the 'ideas' are instead made available for anyone to use, provided that they in turn do the sa

I find your reasoning very strange, if anything, GPL ensures that the 'ideas' are instead made available for anyone to use, provided that they in turn do the same. If anything would be a 'tumor' by your reasoning around ideas, it would be proprietary software, which is what GPL prevents.