Because the sharing is usually implied by the action of liking. Clicking a like or +1 button causes your network on the associated social site to see a link to

Because the sharing is usually implied by the action of liking. Clicking a like or +1 button causes your network on the associated social site to see a link to what you liked in their stream. In theory it's made it far easier to share cool things with people. as an aside, I say 'in theory' because with the millions of 'me too' buttons scattered around the web, in even my modestly small socially networked connections, the S/N ratio has made them near enough useless.