Goldens - especially males - pretty much remain puppy-like for most of their lives. As you said, more than some people can handle. It would be nice if people actually did some research about dog breeds before buying one.
At age 2-3 it is like somebody turns a switch in their heads, and they become reasonable animals (if they are being raised properly). However, you can turn them right back into a rambunctious puppy again by making certain noises, or setting up certain situations. Addressing my 15 1/2 year old lame, deaf, half blind female with an excited “Puppy, puppy, puppy” would send her into spasms of joy, even though she could barely get around. (She died at nearly 16, and we still miss her.)
Have I mentioned that I love Goldens? ;-)