I'm fairly certain that "text to email" is a feature of MMS - I've used it a few times years before iPhones were around.
I don't remember if MMS is enabled by default in iOS but theres a toggle to disable it, and realistically there's very minimal real world use-case for MMS these days.
Yes, it’s an MMS feature. But iMessage makes it way too easy to “text to email” inadvertently when you start a group chat with some non-iPhone users. MMS sucks but it’s the universal way for iPhone and Android users to communicate without needing everyone to be on the same third-party messaging platform like WhatsApp. In my US-centric personal experience, there is no universally accepted messaging app you can be certain that everyone is on.
I don't remember if MMS is enabled by default in iOS but theres a toggle to disable it, and realistically there's very minimal real world use-case for MMS these days.