I actually said the same thing as you in a thread, but I was wrong. Obito didn't form a TSB back then. What he formed was the black mass that he initially used when he was a mindless Juubi Jin, the Kekkei Mora that can't negate ninjutsu and isn't a TSB. Obito only gained 9 TSB after assuming control over the Juubi. It makes no sense for him to make a TSB from just stealing Gyuuki and Shukaku's chakra.i see what you are saying but your assertions is somewhat inaccurate. Obito doid reform them of a sorts. They were initially destroyed by K11 after he formed that sword with them. But he reformed them into the staff after standing up to Madara and stealing back Kurama's chakra from him. So saying they cannot or rather couldn't be reformed isn't entirely accurate.
Ever since Naruto's first TSB got destroyed, which was back during the Madara fight, he never got back one. Unless you're telling me this recharge time is large enough to span from the Madara fight and after the VoTE fight (I say after, because they hadn't reappeared at the end as well), then this is baseless. Nobody in the series has ever reformed a TSB from nothingness. What Obito did I explained above. It's actually assumed they are permanently lost, since the TSB only appear as a set from gaining Rikudou Senjutsu or being the Juubi's Jinchuriki, and have never been freely formed by a user.Now this is just speculation. On my part, but I get the impression they operate somewhat like Sasuke's S/T and need a lot of time to recharge. This might be a product of using Rikudo level techs. Since they are all so OP, once they are used it takes a considerable amount of time to recharge. Sasuke's Tomoe took forever to come back, maybe the same applies to Naruto's TSB?
I wouldn't say extremely difficult, but yeah.But I agree, it's not that they can't be destroyed, it's just extremely difficult to do so.