In countries that do allow software patents, such as the USA, a business branch commonly referred to as "patent sharks" has sprung up: Those companies do nothing but try to patent concepts they foresee will be used in software, and then sue developers who come up with an actual solution.
Those companies don't do any development, their only reason for existence is cashing in on others' independent development, and therefore hinder actual progress.
This business branch must not be allowed to get a foothold in Europe because its interests are the direct opposite of the people's and legitimate companies' interest.