Lol this is me. People who write their SQL from scratch confuse me, I'm like, just use the ORM and then everything's consistent! :P
Otherwise you will never be able to really understand what is going on and will not be able to optimize a complex app that needs to be performant at scale.
Learning both has its advantages and I think an ORM can indeed speed up development, most especially for the prototyping phase.
I used to do a lot of hiring of Rails developers, and always believed (though admittedly not scientifically enough) that the best differentiator between "sorta productive" and "capable of fully independent work" was an understanding of how AR maps to SQL and the ability to know when (and how best) to drop down into writing queries directly.
I've seen ActiveRecord create some head scratchers.
Still, you really need to have a good handle on the difference between operations that build up the query, without executing it, and those that pull the data back from the database. Also understanding what code constructs that the ORM is capable of translating into SQL statements.
The ORM in particular would sometimes cause me to write very inefficient queries. If I understood the ORM better, I probably could have avoided this, but I found it much easier to write a data layer that ran SQL queries directly and supplied the other layers with simple JSON-like objects.