I'll name 4 possible explanations of many. I'm not listing these to justify any behavior, just to explain what I've seen.

1) If the company has someone in particular in mind that they want to sponsor for a visa, they need to prove they couldn't find someone local, so they tailor an unattainable or excessively tight job description. This is real, and happens very frequently.

2) Many companies discredit experience gained elsewhere. "2 years with us is worth 5 years anywhere else." So they set the bar high.

3) HR reps get burned by letting unqualified people through. If they can't understand themselves if someone knows Python, but they know the last 3 peoples with 5 years experienced got crushed in the interview, then they ask for 10 years.

4) Most firms know that employee referrals are the highest percentage shot for good hires of both technical and cultural fit. As such, the external barrier is much higher than the internal barrier. At my current and prior employer, I could get anyone an interview for an open position by dropping their resume off at HR. It didn't matter if they fit the credentials as long as I vouched for them. This helps them avoid point 3, because if the interview doesn't go well, they're off the hook.

We can talk about the injustice of this, but there is a simple answer. If there is a place that you want to work, make a friend there. Or make a friend who has a friend there.

It's an arms race.

I see a lot of CVs and the fact is most people exaggerate their skills in their CVs. In turn companies exaggerate their needs in their job descriptions.

Software can be kind of a "fake it till you make it" industry, and when you're starting out, a big part of that is embellishing your resume. You shouldn't put anything on there that you really know nothing about, but if you can talk about it at least a little bit, its often better to include than to not.

I don't think this is how it should be, mostly because it's stupid and will backfire. If you want only Ninjas, super developers or those crazy things, expecially if you are not willing to pay for what you ask, you will soon find that it's extremely hard to fill those positions and you will miss people that might be still developing their skills but in future will be brilliant developers. I was lucky enough to get hired from a great company that is not ashamed of picking up "new" developers and grow them. This turned out to be a great strategy and I think that in my case worked out amazingly for both of us!

Even if/when the actual requirements aren't too outlandish, the description is just as ridiculous. I read one on here just the other day that was seeking a RoR force of nature - someone who could move mountains, etc.

Who writes this crap?

That is hilarious:))How can you take a company like that seriously?

The worst is ads which say Job requirement for X requires Y or more years of experience doing X.

I mean WTF!