Screaming Penguin - Source Does Matter

'trox,
While I certainly agree with your sentiment, I am afraid that the general populace doesn't. And won't ever, no matter what reasonable arguments you present.
Obviously, if you set up your web-app to accept information that is only validated on the client-side, then you should oh so very much reap what you sow. Gonna get burned, it's just a matter of time.
However, people don't wanna wait for a resubmittal to be told that their phone number is not valid. People want a flashy site that does nifty little things when you move your mouse around. The want all of the glitz and they want to forget that they are on the web. No matter what the general populace says, they don't want to work on the web. They want all of the information on the web available on their desktop, as accessible as their "My Documents" folder is. And they want all the whizbang features that go into desktop apps.
Since that's what the beast wants, thats what the majority of web sites and internet apps give'em. You want fancy-schmancy text in email? Well, instead of inventing something new, we'll just cram in our fancy-schmancy HTML interpreter that is already jammed full of nifty little schmancies. Oh did we mention that the HTML that we use is our own version, and the schmancy-driver, or scripting language, is proprietary too. Oh yeah, and its based on our legendarily safe and secure OS hooks.
The general population makes it to easy for this type of behavior to be acceptable. Again, I am fully behind your rants, but I fear that we are shouting into the fury of the storm. (OK that doesn't sound right, but I can't remember what we are shouting into)

Sigh.....

-jeepmutt