Does that means GPL is more restricted than MIT?
This depends on who you ask, and what your goals are. GPL people like to poo poo MIT by claiming it has weak copyleft, while MIT people like to poo poo GPL by claiming it's viral.
In my opinion, MIT is less restricting and therefore more open. However, GPL's viral effect, means that newly contributed code has to also be open, so it's more force full of the open theory, and therefor more open, even though you have a pinch less freedom with the code. Shrug, it really don't matter that much for me.
My primary concerns with an Open license is very clearly noted in MIT. It specifies that you can use my code with out worrying about me claiming you stole my code or taking actions to pursue you. It also specifies that I offer it with no warranty, or liability, so you can't pursue me if something goes wrong and costs you hardship. Those are the critical components in almost any Open license.
GPL intends to protect IP rights from the developer. So they require a history of the developers. I have a mild objection about this tracking mechanism. I don't have any expectations that the open code or files I release will benefit me by putting food in my mouth, or anything of any real tangible consequence. So I see no personal benefit to me of having that tracking mechanism. However there is a mild chance that it opens me to liability issues. For example, if you use my files to build something then you do something mean/bad with it, there have been times when our legal systems come after an enabler. When that happens, they don't care that I specified that I'm not liable. I don't think it's very likely with an EMS, but perhaps it could be an issue, if one of the big MFG's felt this type of project was a threat to their business model.
Most of this also only applies to software, as hardware is covered by a completely different set of laws and regulations. The strongest protections for hardware/mfg controls are patents. The KICAD files I've released are software so this licensing applies, however the hardware they make is covered by a completely different set of rules.
Any how, enough of this garbage, especially if your in china where your culture doesn't toss you in jail for these reasons. Keep up the dev work, that's much more valuable time.