There are so many reasons for having a website. I have given the reason in the point of view of digital marketing
Earlier people used to ask their friends and families to know about any services/products. They always go for references to know about a product/services. They also go to shops and learn about it.
Nowadays, they google it first. Google has become their first point of contact for any types of references, knowledge, comparison etc
So it is very important to make your product/services visible to them. To make it visible, first, you should make yourself available on the web.
So having a web presence is mandatory.
Create your website first