What is it with .NET that compels you to lie?
Also FOSS and open contribution are different things, as sibling comment notes.
If you think otherwise, I suggest checking if there's any aluminium foil on your head.
Are you actually unaware of this? If so, why? Is it age or have you been sheltered somehow?
MIT license allows this, hence it's not a free software license. Because very large corporations don't like freedom they've poisoned the discourse around software freedom and launched PR campaigns trying to substitute talk about freedom with talk about openness or open source. To some extent they've succeeded, as evidenced by the chatter about it in this thread.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons..."