And some materials may not be legal in your location - whale products for instance - baleen, bone & teeth are all on the 'naughty list' just about anywhere. Whale teeth were quite popular with calligraphers for smoothing out erasures as one example. Seal and whale bone were used for carving thicker items because they have smaller internal cavities compared to land animals - seen much seal bone for sale lately?
Also a very true point!
For museum pieces and archaeological reconstructions, though, it may be possible to get permission to use materials that are restricted normally. Again, there will be circumstances where they can be replaced with relatively little impact on the end product and then some where they are important... so it will depend on whether it's worth to try and get permission (and then source) the materials.
Living very much inland, I've never seen much seal bone or whale bone, by the way...
Or some materials or methods might be prohibitively bad for the health of the user or others, possibly even legislated against because of it: boiling acidic dye liquor in a lead kettle upwind of a children's nursery is deeply frowned upon, but using stainless steel is allowed.
In my university library was a wonderful book from the 1950s extolling the virtues of asbestos, including the advice to use it as a heatshield directly in front of the face, drilling rough holes through it for the eyes. I'd guess that any future archaeological replica might suffer similar issues.
Dare I ask what a lifetime of doing every textile technique by hand would do to your joints?
Yes, that's true - some methods and materials are not compatible with modern health and safety considerations. With some of them, I'd debate the sensibility of the rules, but with others, I whole-heartedly agree. Nobody wants to inhale quicksilver as it boils out from the amalgamate when gilding...
Regarding the every textile technique by hand, I think it depends on whether you overwork your joints, or whether you don't. If you do the same thing for too long in a row, it might be harmful... but "every textile technique" would be a large variety of tasks, so it might actually be beneficial. Lots of movements, but different ones!