I think that Kickstarter does fall into a slot, that of "online store", it is just obfuscated.
Many other companies tried to bamboozle regulators with technology in a similar way. e.g. ebay says "we are not a shop, we are an auction site". But when they have "buy it now" auctions, it looks exactly like a shop, so they are obliged to operate under Retail Selling regulations.
Paypal say "we are not a bank, we are just facilitating transactions between users". Nope, say the regulators, you must be registered under the banking and finance regulations.
Kickstarter are a shop, the regulators just haven't caught up yet.