Recently, the necessity to build a portal for my team to share the current projects and their progress came into the picture, so I tought that this time I could ditch the frameworks and go with the majestic pureness of Javascript.
On the same theme, David wrote the article 'Why you shouldn't use a web framework' a while back:

Why You Shouldn't Use A Web Framework
David Wickes ・ Jul 26 '18 ・ 4 min read
Now, I understand the principle behind the article, and I find it very interesting, so, when talking about JS apps (React, Angular and everything else-like), what are the advantages and disadvantages of writting an app without a framework and would you recommend that/can you give any resources that represent a real world app (not just an issue tracker or todo app)?
Thank you all.
dev.to was vanilla JS on the frontend for most of its history until recently and still doesn't use a "framework" per se, but we do now use Preact for writing new UIs.
I'm not sure I'd skip the framework if you're really looking to be productive. I went vanilla as a forcing function to keep the frontend logic simple and basic while the project's direction, and for the major performance benefits of just not including more code.
If it is indeed simply an internal portal, it is possible that you don't need stateful complicated UIs in the first place and it definitely could make sense to simplify like that.
As things have grown, the original vanilla code is probably the worst part of the codebase, and that is probably tough to avoid.