I heard another interpretation
...
The problem with slavery is that you can capture a highly skilled slave (though this alone assumes that you are invading a highly developed country) and he will likely work for you but you can't raise skilled slaves...
Yes that interpretation is wrong grasping onto tangential details while ignoring actual cause.
It is certainly possible to build a society that raises skilled slaves. This was the structure of ancient Egyptian society. What you cannot do is expected such a society to be competitive with one that frees its skilled labor
Do you know that Egyptian pyramids were built by the workforce primarily made up of farmers recruited from all Egypt, not slaves? This doesn't very well add up to your theory of raising skilled slaves, does it? And if we assume that they actually raised slaves, how they can be considered skilled if they, as you yourself say, weren't competitive? Nevertheless, we should take into account the level of industrial development of Ancient Egypt (or lack thereof) versus Europe after the 14th century (e.g. manufactories appearing in the early 18th century)...
Basically, you can't compare these skills