most sites have urls e.g.:

example.com/object/{ID}/{SLUG}

or

example.com/object/{SLUG}-{ID}

where {ID} corresponds to the object to fetch from the database assuming the database is too big and that's why we don't address the sql using the slug (in some cases the slug even needs some computations to be reconstructed so it's impossible to address using {SLUG} directly). So {SLUG} does nothing practically except for SEO.

Why can't just we use the cleaner

example.com/object/{SLUG}

And when the URL is request, we hash the slug using a 32-bit or 64-bit hash algorithm, and lookup the sql using the hash using an additional integer column in the sql table containing the corresponding hash value?

What is wrong with this idea?