I would tend to agree with you Superawesomemans, but there are limitations with a purely browser based game like BEW.
SITA installs and runs an executable on the system, which could be a security risk for some folks, although I'm confident SITA is safe. It does allow for tracking progress, savegame's, and achievements in a reliable fashion because the executable grants access to creating files on the system that are persistent.
While I love SITA, it had some limitations that pulled me out of the game somewhat, for example there are no image targets. I personally find the ability to click on a woman's lips to kiss her more engaging and immersive than selecting "kiss her" from a list of options like in SITA. This is something that I was disappointed to lose in between Arianeb, and SITA, although I may be in the minority there. Not withstanding, I still really enjoy SITA.
The difficulty in save games and achievements in games like BEW, is that all the information is saved in cookies. That means, the first time the player clears browser history and cookies, all progress, savegames, and achievements are lost. I could fairly easily build achievements into the game, and have an achievements page a player could go to, but since they would be non-persistant, it seems more effort than it's worth, and I'd be inundated with complaints from people losing their achievements, which would probably take a lot of the fun out of it for me. For these reasons, BEW will not have an achievement system...although I reserve the right to change my mind on that if there is an easy, reliable way to implement them.
Of course, this is all based on my understanding of browser games, and how AC works. I'm sure Tlaero will correct me if anything I've said is wrong.
Wolfschadowe