Yes, I think that is true. Speaking from memory, but I've worked on Unix for long, and I think I remember that on some older Unix versions, you had to specify -

Yes, I think that is true. Speaking from memory, but I've worked on Unix for long, and I think I remember that on some older Unix versions, you had to specify -print, otherwise it would walk the directory tree according the conditions you specified (such as filename wildcards, the -o option (for OR), etc.), but would produce no output for that walk.