The dishonesty isn't in "It'll be okay after I kiss it", it's in the idea that it was ever not okay in the first place.
Think about what purpose the idea that kissing it makes it better serves to you, which leads you to use it. The kid won't accept "Aw, you're fine" and therefore you can't help him feel better with that take. However, if you pretend that he really is not okay, then he can believe that, and maybe he'll also believe you when you offer a solution. It allows you to side step the part where you have to convince the kid that he's wrong, and allows you to lead him to a correct conclusion that he's okay. Which is nice, since having your toddler hurt and in distress can be uncomfortable, and we'd often like to get out of that discomfort ourselves.
But that work is where all the cool stuff happens, and that's where you get to teach them the skill of reorienting to unpleasant sensations effectively. The alternative starts with orienting towards our own discomforts skillfully, and then modeling that for them as applied to their problem.
So, like, what happens when your kid scrapes his knee and he cries about it, and he doesn't stop crying for five minutes. When you could have stopped it at two with a kiss. Is that okay, and something you feel comfortable playing with (assuming you see a reason to play with it), or is it something uncomfortable which you'd rather stop?
To the extent that it's the latter then you have you own little puzzle to sort out, and to the extent that it's the former then you have a new game to play with your toddler. When your own emotional take on the booboo and ensuing distress is "Ooh! An opportunity to play! How bad is this one!?", then it tends to come across and the kid can learn that little booboos and a little distress aren't the end of the world and can actually be a fun learning challenge in an interesting sort of way. You get to engage with the experience they're having without trying to minimize it, or to pretend to agree with it, and that gives them a lot more room to figure out if they're actually okay and what lessons (if any) they want to take from it. And you often get really cool experiences, like watching your kid reframe the problem from "I'm hurt and not okay" to "It was scary and I cried, but I'm okay!" and "Can we do it again!?".
In principle, this can result in more distress because there's more willingness to entertain distress, but in practice I haven't found it to be the case. There aren't really any times where I could offer a kiss to make it feel better, because in the cases where it'd work it never really becomes a problem in the first place. Sometimes my toddler will insist that she needs a bandaid to make it better, and I'll give her one even though she doesn't physically need one, but that's very much led by her and the nudges she gets from me are actually away from the idea that the bandaids are necessary.