Informal agreements like this work between people who know each other, not for agreements between strangers. The terms in an open source license are intended to be universally applicable, to make the obligations clear for anyone who reads them. This includes total strangers and companies that didn’t exist when you published the code.
Those strangers shouldn’t be expected to abide by anything not explicitly written down in the license. If the license doesn’t document the obligations you expect of anyone, you used the wrong license.
We should be suspicious of people who try to claim that there are additional unwritten obligations for reusing source code. Open source licenses have very generous terms, maybe too generous. They allow takers. That’s how it works, you can take it.