Because you also have to crouch — in addition to jumping and shooting at your feet — in order to reach the highest jump length as soldier, some people have resorted to scripts or binds to streamline the process into one keypress. I have heard that using a bind significantly limits the player's ability to jump and should thus be avoided — is this correct?
Personally, I'd say it's all up to personal choice.
I do not use them myself because all it really takes is a little bit of practice to get down. Once you know how to do it, you won't need to use a script.
Besides, there are also more advanced rocket jumping techniques that require more practice to get down, such as pogo's, syncs, speedshots, c-taps, wallpogos, most or all of which require more than a simple bind to be able to efficiently do, so using scripts to learn how to jump high might only be useful for you if you are new to jumping.
Some people are used to using Crouch and Jump separately, and some code it in as soon as they know about it. I find that it is up to personal preference - using it with code does however allow one finger to be free, allowing you to use buttons near CTRL easily at the same time as rocket jumping - eg: Shift may be used for a chat bind