From the USGA website:
A scramble is not played under the principles of The Rules of Golf
For me, that pretty much sums it up! But, unfortunately scrambles have become deeply embedded into the world of amateur/club golf. When I was in my 20's(30 years ago) you could play locally sponsored amateur medal and match play events all summer long. They're still out there but only a handful compared to yesteryear. Scrambles, you can easily play in two or three a week all summer long they have become so prevalent.
I think the golf courses prefer scrambles as well because it's not just a golf tournament but also involves banquet/food sales and lots and lots of alcohol sales. All good for their bottom line.
Personally I only play in one a year and I will continue to play in it because it's for a friend at work who lost his daughter to cancer. It's for a great cause and to support a friend and I take the whole scramble thing with a grain of salt that day. There's always some contractor that puts a team together and shoots -50 under(obvious exaggeration) and some people grumble cheaters under their breathe but I could care less. None of those amazing "scramble" golfers ever seem to show up for any real tournament stroke play events in the area.
My definition of Scramble: A drinking event that is tagged with a good cause that involves striking a golf ball and or "filling out a score card", lol! So just go out, have fun and a couple drinks(responsibly) and walk away knowing you gave something for a good cause that day.