why Hono client take baseUrl as argument

[lord007tn]

in docs:
const client = hc<AppType>('http://localhost:8787/')

this is valid and good in case of fullstack app
i tried
const client = hc<AppType>('')
and it worked as expected nothing went wrong
my question is why do we need to add URL to hc

whats the effect of it

and in case of multi tenant e.g integrate hono in vercel/platforms
will it have effect on the project