So many ridiculous presumptions on both sides in this thread that I don't even know where to begin.
"Reveal how you feel from the start."
You don't always start out knowing that you want to date someone. It rarely goes beyond "I'd fuck him/her." at first sight, and as long as nothing vapid or dense spills out of their mouth when you first talk to them, it's hard to make a snap judgement about whether or not you want to be in a relationship with them, outside of that initial "I want to fuck them."
If by "from the start," you mean "after a few dates," or "after X amount of days hanging out," then sure, you might have a point. Jumping to conclusions right away however almost never leads down a happy road.
"You can't be her friend if you want to date her."
Absolute bullshit, to be honest. I've dated plenty of girls who I considered friends. Whether or not they always regarded me in the same fashion, I can't say. I don't think I'd want to date a girl who wasn't, at least on some level, my friend (or at least one who seems like she would make a good friend). You can't exactly blame guys for wanting to date girls who they are good friends with, it seems ridiculous to me that such a statement would even be made at all.
Shocking news, not every guy who asks a good friend out is a manipulative scumbag trying to get some action. In fact, I'd wager that a majority of manipulative scumbags are probably doing things that are much more productive as far as that is concerned, like picking up drunk girls at a party, or preying on girls who are having a rough time. I really doubt that most of them would waste their time establishing a "fake friendship" in order to eventually, maybe, have her reciprocate with sexual favors.
More often than not, I'm willing to bet, the guy who goes into a friendship hoping for a relationship is simply one who is inexperienced, shy, or socially inept in some way. Demonizing them like they have been in this thread seems to miss the mark, and may even be harmful in some cases.
I don't think that they mean any harm, they are simply expecting that the friendship will turn into something more over a period of time. Obviously misguided, but for a lot of people, especially those with little to no experience, can you really expect otherwise? Whether they have low esteem, are unattractive, are socially awkward, or whatever, if they have had no luck repeatedly with the "traditional" way, can you blame them for trying something different? It's very likely that the majority of these guys are not conniving, and most certainly are not trying to hold a girl hostage emotionally. For someone who likely struggles with talking to girls at all, do you seriously think they have it in them to be a predator? Obviously some do, but the majority of them? I seriously doubt it.
I don't know, the whole situation is shitty, and as a guy who used to repeatedly fall into this kind of thing when I was younger, I think that immediately painting them all with the same brush is more than a little silly. I harbored no ill intentions or sinister plans when I tried to approach dating like this, I was merely inexperienced and had little luck with the traditional method of being upfront and forthcoming about my feelings right away. I think we would do well to try and understand why it happens a little better, rather than jumping to silly conclusions that end up hurting everyone involved.
Reading this again, it turned out to be pretty incoherent, but oh well. I just wish people wouldn't be so aggressive and judgmental about any of the people involved a situation like this. It's usually a lot more complicated than it looks on the surface, and many times there are no intended wrongs by any party.