Gengis
What a complicated and beaurocratic mess
There is a perfectly decent, safe and proven model for all this, where to fly in clouds you need an ICAO IR, and that's about it. Unfortunately it's 'over there' so in the eyes of many must be inferior.
I guess you are saying an IR3 (airline pilot) is better than an IR1 (warrior pilot). Do you think that a 737 pilot who never flies a PA-28 is going to be better/safer at flying a PA-28 to 200ft DH than an IR1 who does that every other day? It's not so! Type ratings are the way to introduce this IR1, IR2, IR3 complexity. Insurance companies are also effective at mandating training for the IR2 type of plane, as would be actual testing of IR skills on a multi engine plane before you could fly it.