Well, yeah, sorta.
The problem is that it *looks* easy, and mechanically, it's not that bad. The problem is that there are a dozen ways to screw it up, and just seeing data through it isn't always a good indication that it was done right (especially with cable used at 100Mbps +).
Cat5e connectors have the little "sled" that the wires feed through, it's a pain to get that located properly (until you've done a few dozen), most new/first-time crimpers don't get the strain relief right, many/most don't even know about the pair-ordering and usually end up with a split pair @ pair 2.
Many/most folks I see getting ready to do their own cables don't know that there's a difference between the cheap RJ45 connectors and the Category-rated ones (that are much more expensive) ...... so they buy the cheap ones, and shoot the Category rating down to "nothing" (unrated cable).
Many/most folks see data getting through, and assume everything is fine ...except they're getting 10meg or less because of some mechanical/electrical violation.
For the expense of buying decent tools and supplies, and the time it takes, it's usually just better to buy the cables and be done with it.
Wiring your own home? yeah, sure, no problem ... most of that will be punched (much harder to screw up). There are still rules/guidelines, but they are easier to implement.
Mucman: "I'm everywhere"
FWIW
Scott