I gave you a nice date picker to use but instead you choose to type in the date. Type in an incorrect date and then yell at me for it. If I could enter the dates for you , you would not have a job .... stupid users

45% of my time is spent compensating for the "quality" of my users.

Another 45% is spent overcoming user testing that didn't reflect real-world use.

10% is spent drinking coffee.

I really miss developing new code....

So u allow the users to type a date but was lazy to add validations?
Sure you gave them a fancy datepicker, but did you consider how many clicks it will take to get to 1/1/77 compared to typing it in ? Not to mention the stress it generates on the wrists when switching from keyboard to mouse and then back.

@kaqqao he inferred it from the rant because if there was a validation message saying the date is invalid the user would know that's the problem and wouldn't yell at OP. Problem is, the message could be not clear, the user maybe didn't understand why the date isn't valid, the user maybe wanted to be able to enter date in a different format, ...
However, I still agree that a datepicker should not be relied as input as I've never ever seen a datepicker I like... I always prefer a well implemented masked textbox.
And, while I absolutely share the OPs sentiment as I deal with the same things, at the same time we have to realise that if the user wanted to think about what he's doing when using the app he'd just use notepad or something... It's up to us to guide the user in such a way that they don't make mistakes in using the app, otherwise our apps are not as good as they should be. Of course, UX designers are more important here, but we need to implement the UX properly.

The validation consisted of making sure it was a valid date. The error occurred when instead of clicking march 28 2017 he typed 03-28-2011. It was also masked so he could only type the date a certain way and in turn he typed the wrong date for 100s of entries because I also gave them the option to apply the date to all items on the page so you don't have to click 100 times if the date will be the same.