According to YouTube, the update is to mitigate harassment and dislike attacks.
In a nutshell, he stated that the removal of dislikes prevents users from quickly identifying bad content.
The dislike button itself still remains intact and, if you negatively react to a piece of content, it will affect your future recommendations , but you cannot see how many other people have used it.
And the more users there are - the more accurate will be the estimation.
As it stands today, data only updates once every few days.
In a nutshell, this means that the data you see here will be entirely accurate.