GPL would not solve the problem Elastic has - it's perfectly legal (and in the spirit of the definition!) to take GPL software, host it yourself, sell the hoste

GPL would not solve the problem Elastic has - it's perfectly legal (and in the spirit of the definition!) to take GPL software, host it yourself, sell the hosted service, and not pay the creator a cent. It's also perfectly legal to run GPL software on a Windows machine without open-sourcing Windows.