In the World Assembly - both GA and SC, though arguably to different extents - we have the difficult problem that out of probably a little under 10,000 regular voters, only a handful put any effort into informing themselves about the resolution at vote, whether by researching the topic online for the GA, finding out about the players and events involved for the SC, or by reading the WA forum discussion in general. The game's solution to this is to have regional WA delegates whose votes are weighted by number of endorsements. The top few delegates all hold significant power in determining the way a vote goes; this power gives them a responsibility to vote in an informed manner and I think it's fair to say it is therefore at least an attempt to make the actual outcome more reflective of each resolution's quality. In practice, most if not all of these powerful delegates are leaders in a region which will have a government set up on an external forum and their vote might be decided by a WA ministry, or by citizens, or whatever. And so, especially where the former or something similar is true but even with the latter, big regions also get a louder voice to project their political views and stances and their foreign agenda; this is particularly relevant to the SC but can also apply to GA proposals depending on authors.
That comes into effect in the actual voting - as Fregerson says, an early stack or stomp can really leave a mark - and in IFV production too. I don't think I can really get numbers to back this up but I suspect that a lot of people's votes follow the IFVs they see. That's a good thing in that an IFV dispatch will definitely inform a voter more than they would otherwise be, but often the perspectives the average voter will get might be pretty one-sided. Right now in the top 20 dispatches we have TNP IFVs for the GA and SC at vote, a Europeian IFV for the GA at vote, and a TRR IFV for the SC vote which just ended. And that's it. That gives those regions' WA ministries quite a bit of sway in quite an unbalanced way, so any region which puts together a dispatch program and a well-organised UpVoting team has good opportunities there.
Voting blocs can certainly help push or block a resolution via a stack or stomp respectively. They will likely always be made up of similarly minded regions so on a regular basis probably do little to change the situation, but as necessary can be helpful for setting up a concerted effort to get an early stack or stomp, and I think on the voting floor that's their chief value, as well as helping gather/prevent approvals on submitted proposals.