Help me get over that (pay)wall

Why can’t brands sponsor my access to paywalled content in exchange for attribution when I share via Like/+1/Tweet buttons?

Clarifying – i don’t mean brands should pay me to share. I mean:
1) brand buys bulk subscriptions from site & gifts to high value users 2) when these users are logged in & share from....said site, the share box contains brand attribution. Brands incr need to create, or wrap themselves around, content…..banner, interruptive, etc advertising is going away or prices towards $0. Isn’t my suggestion just another version of……site sponsorship/takeover that advertisers love for share of voice & engagement?