I'm not quite sure what you imagine "become a handicap" would look like, but the overall concept here is pretty simple. Technology changes pretty fast in the website development world. Whether you target the bleeding edge, the most broadly adapted standards or even if your target is legacy browsers the bucket of available technology tricks is quickly advancing. Whether you are on the front lines with the cavalry or running rear guard behind the main troops, the field in general is covering ground pretty quickly.
This has obvious implications for the toolbox of any developer. The most advanced sites are almost always going to be hand tooled. By the time the available automated tools catch up with the latest possible technology, the tech has moved on. If you want to crank the most out of the web, you're going to have to get your hands dirty.
On the other hand there will always be a large body of tools to available to support development in the middle flanks. These tools will always have different strengths and weaknesses and are better suited for some purposes than others, but most will get the job done one way or another.
On the other hand if you tie yourself down to a tool that stops getting updated, you're going to get stranded. Even the main body of troops are going to pass you up and you'll find yourself without supplies in a land left trodden and barren. Sure you can eek out an existence there too, but you aren't going to be doing yourself, your customers or the world any favors.
Any tool that stops being actively developed is going to hurt your long term ability to participate in the field. As a developer, one thing you need to do is develop yourself. If your toolkit stagnates, you aren't learning anything new. If you aren't learning anything knew, eventually there will be no market for your skills. Your product will see increasingly less demand and eventually you'll actually be harming your customers interests rather than furthering them.
This is not an argument to stay on the bleeding edge. That is for pioneers. But no matter where in the ranks you place yourself you should be covering ground. If your toolkit isn't keeping some kind of pace, eventually it's going to be holding you back.