It's impossible to say for sure, without knowing people's behavior and motivations.
In the past, I've certainly been more likely to buy software if I see it's cross-platform, even if I know I'll never use it on those other platforms. Or it might be a corporate requirement. There are many possible reasons.
For example, if a restaurant serves only steak, is it a net loss for them to put a pasta option on the menu, if they know they'll never sell enough to make up the cost of ingredients and preparation? Maybe not -- it could mean a party of 10 (with 1 vegetarian) is willing to eat there, when they otherwise wouldn't have been.
