You seem to take pleasure in finding fault. The following is a more complete explanation, written on a different forum.
' SMS messages are restricted to 160 characters. While iPhone users with iMessage can send any length they wish. While some non-iOS based phones and carriers will handle them differently, many will break them up at the 160 character limit. If you are sending a long message, that would explain it. You can contact your carrier and ask them, but SMS is a carrier feature. There is no setting on the iPhone for handling SMS.'
I don't know why you've never come across this, but I experience it myself when getting long texts from iPhone users. Your jumping the gun to find fault is counterproductive to find a solution for the op. This is for the op, right?
I'm not taking pleasure in finding fault. I simply say you are wrong. You're the one jumping the gun saying it's an iPhone fault when clearly this was not an issue on older versions of the Samsung Messages app.
Samsung phones before Nougat doesn't have this view all. I've had Samsung devices for 7 years and have been texting very long messages with iPhone users. You can get a 450 character long SMS on a Note 2, Galaxy S5 and S7 (on Marshmallow) without the view all button and it just shows up. Again, this view all button only appeared on the version of Samsung messages for Nougat and beyond.
That explanation you mentioned doesn't even concern this issue. What happens when carriers handle long SMS either you get one long text or multiple short ones. It has nothing to do with how the SMS app shows this. If that was the case, then it should have been the same whatever SMS app you use, which is not true. Android Messages and Textra do not have a view all button. Samsung designed their new SMS app so that long messages will be truncated and hidden behind a view all button, which is different from their old approach where they will simply show everything.
I happen to have an old S3 lying around and I can test this freely. The following screenshot clearly shows a long message without the view all "feature" on an older Samsung phone.