The very fact that you have a body accrediting programs means that there will be many schools serving up engineering degrees that are not accredited by ABET or one of its member societies, especially internationally. Are these people suddenly not engineers just because a licensing body has not bestowed their program the honour of accreditation? Just because there's an accreditation board does not suddenly make it the only ruling body on who can use the title "engineer". Unless it's actually illegal to be an engineer without being accredited by ABET, then their word really means jack shit.
> there is such a thing as software engineering
Which differs from place to place, yes. Not every program has been accredited but still provide software engineering degrees, perhaps with elements that would not be found in another's curriculum.
> and the people most strongly insisting to use the title don't practice it
Just because you don't have an accreditation does not mean you "don't practice it".
> Like I said, you can legally use it, but licensed engineers are rolling their eyes when your back is turned.
Good for them. They can roll their eyes all they want, it doesn't make them more right to do it.