As i observed, lot of questions on Magento 2, title ended with Magento 2, even we tagged as magento2.
Can i ask a question by having Magento 2 at the end of the question ?
Will it help Seo when looking for Magento 2 related question ?
Yes, you can ask questions that contain "Magento 2" in the title. It is not encouraged because version numbers can be added in the tags as you say, but it is not forbidden.
As for SEO, I don't know if it helps or not.
I think the SE network does a good job for SEO anyway.