I would consider myself quite up-to-par with the concept and in-depth functionalities of SegWit (segregated witness).
I just don't understand one key aspect of it; P2SH and bech32 addresses.
- why on earth was it necessary to create new address formats, what does that do for segwit?
- Were the new address formats made as a reason to help segwits implementation, or do they serve a different use-case. (i.e similar to segwits transition to "weight" which had nothing to do with fixing tx malleability but rather optimizing blocks).
I don't see how a P2PKH address couldn't be used in a segwit transaction. The ECDSA signature is still the source of validity of a transaction in segwit