If scrolling isn't recommended for user requests, what to use?

No, there isn't another way. Scrolling is probably the thing you want to use if you really want to do it. But you've found a thing that Elasticsearch doesn't like doing very much. To us, getting all the documents for a user request is a use case we barely support. We push people to use aggregations if they want to do things across many many documents because that is much faster.

Usually for a search use case you limit the depth you allow users to search. Like this or this. The last one actually uses Elasticsearch....