Remember when Bill Gates started his new life as a philanthropist by donating tons of money to schools? Only it wasn't really money. It was lots of Windows licenses or Office licences that were worth a lot of money. So it arguably didn't cost Gates anything, but just grew future earnings. He kept all these students from gaining familiarity with the competition, encouraging them and their employers to buy licenses later for the product they had learned as a child.

There's the downside.

Short answer: Their software will lose mind share, and therefore market share in the long run.