I'm surprised this opinion has so much uptake. Ideally, we would all be highly informed. The reality however is that most of the voting public will not be, and your informed vote has no more weight than an uninformed one.
I don't like voting based on party, and I think the two-party system we have is inadequate, but the parties are there for a reason. I know that I'm voting for a platform if I vote for a Democrat or Republican or Libertarian, and that the candidate is going to represent that platform at least to some extent. In most cases, candidates' platforms are drawn directly from the party platforms, and you're not likely to find out much more about them until they've been in office for a while. Even then, what is knowable about a candidate is mostly in aggregate.
As to actual issues, these can be much less straightforward, but often it comes down to something as simple as, "do I want gambling at the mall?" (a current issue in my district). There are a lot of implications behind this - money coming in from out of state to protect other gambling interests, developers who want to build, etc. - but I still think it's valid for someone to vote for or against it for their own personal reasons. It is an expression of culture not just reason.
I'm voting for a platform if I vote for a Democrat or Republican or Libertarian
That's true to a certain extent. But it's only one side of the equation. Even if you can take party as a proxy for the candidate, it tells you nothing about the issues.
So, let's say that your biggest concern at the moment is the economy. Without knowing something about economics, how do you decide which party to support? If you can't tell the difference between Keynes and Hayek, everything else is just demagoguery. You're just judging the propaganda.
What if you're concern is healthcare? I know plenty of people who say "vote out the damn Democrats, and put in somebody who's smart enough to enact tort reform to fix the problem". These ill-informed views might make them feel superior, but giving people power to create policy based on them isn't going to help anything.
I don't like voting based on party, and I think the two-party system we have is inadequate, but the parties are there for a reason. I know that I'm voting for a platform if I vote for a Democrat or Republican or Libertarian, and that the candidate is going to represent that platform at least to some extent. In most cases, candidates' platforms are drawn directly from the party platforms, and you're not likely to find out much more about them until they've been in office for a while. Even then, what is knowable about a candidate is mostly in aggregate.
As to actual issues, these can be much less straightforward, but often it comes down to something as simple as, "do I want gambling at the mall?" (a current issue in my district). There are a lot of implications behind this - money coming in from out of state to protect other gambling interests, developers who want to build, etc. - but I still think it's valid for someone to vote for or against it for their own personal reasons. It is an expression of culture not just reason.