The original 777 was planned to have folding wingtips ( circa 1992-93 ), but at that time for a variety of reasons, the folding tip was dropped. at about that same time, winglets for 737 buisness jet was aborning, mainly for" looks" to differentiate from ' commerical' 737. Sort of like executive perks like chrome hubcaps. The agreement was that as long as it did not degrade performance and looked neat, winglets would be an option. Internal battles with certain aerotypes who were pushing a new wing for 737 at a horrendous cost eventualĄ resulted in a series of flight tests with winglets. And the results were such that they eventually became ( long story short) an option for new commercial 737. meanwhile back at the ranch, raked wingtips were aborning. And for long range commecial routes, the raked tips were perhaps a bit better than the winglets. But apparantly a significant redesign of the metal 777 wing would be needed to accomodate the raked tips.
Along comes the all ( mostly) composite wing, and along with better control via layup and molds of wing contours and smoothness, the raked wingtip could be accomodated- and because of airport clearances, the folding tip became practical again.