Maybe, maybe not.
There is power, they perceive, in having you there. They think they have the most power. It's not that they don't want you to have anything in writing until you sign the contract; no, it's that they want to give it to you in person and have the chance of talking you into acting on that information immediately.
I will never *not* participate in that game, because I know what it is--and I am perfectly capable of saying, "no". In fact, I have a core philosophy: if you have to have an answer right now, the answer will always be NO.
But the buyer has power in this situation as well, and that power is not to be dismissed. It's much more power than either side has in a simple faceless email transaction.
Coming from a lifetime spent in and around the retail end of the car business, I can tell you this: the only reason that some dealers insist on doing face-to-face negotiations is that they want to get you to fall in love with a car, confuse you with payment numbers, pad your interest rate, and every other dirty trick they've been doing since the 1950s, which is the era that many of them are still stuck in.
You may have the ability to say "no" and walk away whenever you like, and many others have the same willpower, but there is no part of the new car sales process that cannot be done remotely, with the exception of test-driving the vehicle (optional) and signing the buyer's agreement. As I mentioned previously, I said no to several proposals via email and online chat, and without fail, they came back with a better offer.
The days of going to a store and talking to a salesperson to buy things like televisions, appliances, mattresses, and most other large items are over. There's just no need for it anymore. Want a better deal from a website? Put the items in your cart and then leave them there for a day. If you've already got an account on the site, you'll get at least a 10% discount code emailed to you within 24 hours. Got the new TV and you don't like the picture? Return it.
I remember the turn of the century, when my mom was adamantly against buying anything online. Now she does every bit of her shopping online with the exception of groceries, because the only businesses that are as stuck in the past as many car dealerships are the organic earth-friendly grocery stores that sell the free-range vegetables she likes.