It is well established that agreeing to some conditions doesn't necessarily make those conditions legally binding. There are many circumstances under which they are not.
Interfering with this process reduces freedom.
Interfering with freedom is necessary, almost everywhere. The very fact that two people can come to an agreement that they would expect to be enforced is a massive interference in freedom. To say nothing of that fact that you seem to be happy to interfere in someone's freedom to tinker with things, but not happy to interfere in the freedom to restrict that freedom. Do you want this "freedom" of yours or not?
If a contract contains terms which are illegal or become illegal, depending how the contract is written it may in whole or in part be nullified.
It's seen a lot in apartment/house rental contracts, where the renter puts predatory terms in a contract which aren't allowed by local or state laws. They try to enforce because "you signed it" but a challenge in court sees the contract, or at least those terms, scrapped.
Interfering with this process reduces freedom.
Interfering with freedom is necessary, almost everywhere. The very fact that two people can come to an agreement that they would expect to be enforced is a massive interference in freedom. To say nothing of that fact that you seem to be happy to interfere in someone's freedom to tinker with things, but not happy to interfere in the freedom to restrict that freedom. Do you want this "freedom" of yours or not?