Agreed. The fact that it's harder to do on the web for whatever reason shouldn't mean they get to ignore the rules.
I see this sort of paradoxical mindset all over the place: X breaks the rules but X is just so successful, or so full of potential, so shouldn't we just bend or break the rules for it? But the fact is that X is probably successful or full of potential in large part because it's been breaking the rules, and the rules exist for a reason.
If there were rules governing political ads in social media, they would look very much like Facebook's policy. At least TV ads (which are more tightly regulated due to the use of radio spectrum, which are public goods) are regulated as to force TV stations to air even political ads they deem untruthful:
I see this sort of paradoxical mindset all over the place: X breaks the rules but X is just so successful, or so full of potential, so shouldn't we just bend or break the rules for it? But the fact is that X is probably successful or full of potential in large part because it's been breaking the rules, and the rules exist for a reason.