After you file

Hi,

I have been asking this same question from different tax experts and they all been telling me I don’t need to do dual status tax return they say since I have green card on the last day of year 2019 I will be considered a resident and can file 1040.

I am so confused and I need you to help me, if I file my 2019 tax using 1040 only, would I be in trouble? Could you please argue why I need to file as dual status? 
Thanks ,

samira