Proxlet never made any attempt to block ads (they didn't even exist when we built it!) That said, it's really no different than a normal 3rd party app which could do the same thing. Again, my beef was the manner in which they shut it down abruptly stranding users.
TweetFavor just supports an existing pattern "hey dude, can you tweet this for me?" And permission had to be given per-tweet request, there was no mass zombification. You'd pledge individual tweets. Once again, no reason as to why it was shut down, and certainly no one used it before making the call.