For context - I'm half Irish half Italian, raised speaking both English and Italian, but went to school in Ireland.

My English has a natural Irish accent because I grew up there, and while my Italian was pretty much fluent, when I moved to Italy at 18 years old my accent was not 100% perfect. When I first moved over, I couldn't even hear different Italian regional accents (because I had a very limited input from only family members and some TV).

The more I lived there, the more varied input I got, the more I was able to easily differentiate different regional accents, and the more I actively tried to copy the accent of my friends from my city. My accent now is pretty much perfect and I'm never "caught" as a "foreigner" even after telling them.

But:
- I already had a solid foundation, even though 18 years of output were with a questionable accent
- I actively tried to copy the accent around me to improve mine, this wasn't difficult once I was able to hear it

Now I am trying to learn my 5th and 6th languages from the beginning, and improve the accent of my 4th (which I've been learning "traditionally" for 20 years, and my accent definitely sucks).

My question: Does input really give you the best natural accent?

I ask because I know many Italians who have moved to Ireland many many years ago, and have a very advanced level of English, majority learned naturally in the environment, but almost all of them have the strongest fucking Italian accents I have ever heard.

Can we really blame "early output" only on such a huge difference between a foreign and native sounding accent, when probably everything else the majority of them did was in line with input based learning?

(Ok, they didn't listen to Anime all day, but got constant input in work, social settings, navigating life admin, etc, most of the people I know had a very basic level of traditional study but for a very short amount of time.)

After 10, 15 years of hearing native English speakers around them constantly, is early output alone to blame? It seems like too small of a factor in the grand scheme of things. The majority do not seem to realise how strong their accent is (I've had a couple Italian friends comment on other Italians' accents, laughing, without them realising that their own accent is just as strong).

I also assume many are probably not trying to actively copy those around them.

This leads me to believe that accent acquisition needs to be a lot more active and forced than just naturally acquiring a perfect accent by avoiding output, mass input does not seem to be even close to enough.

What do you think?