So Juliet deleted all traces of MC from El's phone and even "reset" it to make sure it stuck, but most phones are connected to a cloud server that don't delete stuff even if they are synced up unless it's manually done, and even though she is a diabolical witch, I hope she is as technologically blind as most boomers out there and she just signed out of El's accounts instead of going even deeper. That some history that belonged to El remained for them to be able to return to.
Not just photos of MC, but also of their cat, their friends, their own personal and professional life. Juliet didn't just isolate El from MC, she also isolated El from their real life, their hobbies, their job, and in a way, from a way to heal from their trauma. It's easier to ground yourself to life when you know you have people who know, love, and wait for you. El, right now, has no one but the echo chamber Juliet built around them.
Also, I'm wondering: how much of an amnesia El does have? It seems pretty selective, mostly retrograde amnesia but only for MC and the life they built? But MC has been a part of El's life for many years, including childhood/teenhood, if I recall correctly from Juliet. They seem to remember April the baby, a brand new addition, and her parents, old friends but not that old, and Robin, an ex, but not the person that has been a part of their life for so many more years? They don't even seem to remember MC as someone they used to know, MC seems to have been completely erased.
Now, I know this is fiction, and this is basically what's called "Hollywood Amnesia", which is medically incorrect amnesia done for drama reasons, so I'm not too bothered, but I am somewhat confused by how much El actually remembers, and how much they forgot, and how much of it is permanent.
[Personally, I don't agree with you that El forgot all of MC permanently (which is what you basically said in the past, this could have changed by now, of course) because of how long they have been a part of the Winters' lives, tbh. I believe some of their memories of MC have been blocked off rather than forgotten due to PTSD because they called MC during their "last" moments before the call dropped.]
Juliet was thorough on the phone—I thought it made more sense that way since El lost a few years, not their whole life. El could've been able to reconnect to their account and see everything, which Juliet wasn't about to risk. That's why she wiped it all. But yeah, I agree that what she did wasn't helpful at all for El, and that's why there's no redemption arc for her.
El and MC are not childhood friends, nor have they known each other for much more than 3 years—if I stated otherwise in LAD, then my brain was probably not braining, but I don't think I did, haha. El didn't just forget MC, but also Ekissa, Vailyn—anyone they met during that period. Also! Remember that El's first POV in LAD takes place months after the crash, so they had time to learn about April again through the couple (so kinda reintroduced).
It's written in El's POV in LAD that they have fragments of memories, like MC's voice. I answered something similar here. And in this case, El won't recover their memories. Fragments don't mean full recovery and PTSD amnesia can sadly be permanent.