In the sense that when people want to use a piece of MIT-licensed software in another piece of software, they don't in practice find themselves restricted from doing so by the conditions of the license. "Permissive" might be a word I should rather have used.

The MIT license does place one specific license restriction on its users. Specifically: "subject to the following conditions: the above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software"