Most definitely you do need scales. There are many who would argue that no you don’t need scales.
Many self-taught guitarists claim that they don’t know scales, never have, and don’t need them. Of course every time they play in a different key they are using a different scale.
Knowingly or not they are using a different scale.
This brings us to why scales are needed.
You are jamming with friends or someone at home wishes to sing to your playing. You need to play in a different key.
This is easy when you know scales. you know which notes should be flat. Which notes should be sharp and which notes are not. It is easy to play in another key.
Now, if you don’t know your scales and you learned a song in the key of C Major. How can you play in D Major if you don’t know the notes involved?
With scales life is easy. You do not need to know them all. Learning a scale a week will soon get you up to speed as to the most regular scales you are likely to use.