That is not necessarily the case.
Sometimes you have teams that are all just heavily piled on top of windmill, and your team isn't get to get them off of it without getting completely wiped.
At times like these, you can instead go bottom, and just 4-5 man their bot point.
This will force the top defenders to move their complacent asses off the top point and cause a bit of chaos or confusion, and you can use that opportunity to head back up to top while they are trying to hold bot and get it that way.
OR, if the defenders stay top, you get their bot point, and now *your* team is the one with a 3 cap, and the enemy team has to be proactive instead of lazy.