I am asking this question due to this answer.
Is the removal of identity view (sakkāya-diṭṭhi) required before stream entry can be attained? Or would identity view be removed only with the achievement of stream entry?
To me this question sounds like an example of reification. In my opinion, in real life the numerous factors of Understanding and Liberation develop gradually, supporting each other in lockstep.
The more someone sees through the numerous simplistic assumptions underlying our idea of "self" - the more one can be said to be free from the self-view. In practice the stream-entry is gradual, just like Enlightenment itself (I believe).
The entire maturity model is pretty much a reification - defining clear-cut categories where even the criteria for delineation are not well-defined. This is why in Mahayana we are advised against obsessing over categorization too much, because it can lead to dead-end arguments, but also supports the self-view. On which level am I? - this very question already presupposes existence of "I" that can occupy a level.
I think the whole model is a bit sarcastic on Buddha's part towards the junior students (and Buddha WAS known for his sarcasm) in the spirit of "oooooh, sounds like you still have many more lives to go, brother" etc.
Sakkhaya Ditti is eradicated as a result of attaining stream entry. It's wrong to say that it is required to remove the identity view before attaining stream entry. Read the detailed answer given here by venerable Yuttadhammo.
Stream entry is a label to concisely announce that the person has the usual 3 characteristics of ''stream entry'', with what you call the lack of ''sakkāya-diṭṭhi'' being one of those.
If you want to know what the lack of ''sakkāya-diṭṭhi'' is all about, which has nothing to do with being an expert on dependent origination like it is written on another thread on this website, you can read https://www.accesstoinsight.org/tipitaka/sn/sn22/sn22.089.than.html and his statements like
"In the same way, friends, it's not that I say 'I am form,' nor do I say 'I am other than form.' It's not that I say, 'I am feeling... perception... fabrications... consciousness,' nor do I say, 'I am something other than consciousness.' With regard to these five clinging-aggregates, 'I am' has not been overcome, although I don't assume that 'I am this.'
that's all there is to the lack of ''sakkāya-diṭṭhi'' . the lack of ''sakkāya-diṭṭhi'' is itself a label regrouping all the statements in this quote.
I you want to now what ''''sakkāya-diṭṭhi'''' is all about, since you are a puthujjana, you already naturally regards the ''5 aggregates'' as ''I am this'' and even more stupid from you, you turn that into a ''I am'', typically by regarding as and calling them ''mine''. You have been doing this for many years already, so no need to explain more. Once you no longer regard any aggregate as ''mine'' you can claim that you lack ''sakkāya-diṭṭhi''.
SN 22.122 states that meditation over five grasping aggregates is a continuos process. It applies to all , stream enterer, once returner, non returner and the perfect one. Meditating on five grasping aggregates leads to the fruit of stream enterer, once returner, non returner and perfection. I answered a similar question here. Although nothing is left for the perfect one to achieve,eradication of self view is a desired meditation even for the perfect one.