No, it is not.
What about this situation: You're a construction worker and at some point during your workday, you find a smurf and attach it to the hammer you were using to do some hammering. The smurfhammer proves to work ten times better than the smurfless hammer -- a great invention!
According to your reasoning, the company the construction worker works for now owns the smurfhammer (2000). What's worse, all employees are discouraged from ever thinking up and using smurf-augmented tools on the job. If they do, they'll have to surrender their inventions and the IP. So the company actually suffers from workers afraid of being (smurfwielding) geniuses on the job. They save their genius for when they don't need to hand over the fruits of it.
Now, most construction workers don't often make such advances during their work (there is a clear lack of smurfs on most construction sites), but in software development, there are many many instances of creating domain-independent tools to achieve the domain-specific needs of the employer. Both parties benefit from the freedom of the developer to put as much of his/her skills to work as possible.
I've personally entered a number of contracts in which there was an explicit separation between the domain-independent and domain-specific elements. The thinking is that the stuff that I created specifically for the other party was the result of a collaborative design process with that other party and that it was what I was hired to do. The other party owns it, but I have the (lifelong) right to reuse the code in other projects, as long as those projects do not compete with the core business of the other party.
On the other end, the other party received a lifelong, transferable right on the domain-independent stuff I wrote (but I retained ownership), as if they'd pulled an open source library off of the net.
Effectively, you agree on dividing your work between a general purpose library and domain-specific code. I believe and find it works quite well and is an honest reflection of the merits and efforts of all parties involved.