Linkedin is just glorified contact list. People lose their email addresses, change emails with a job, lose phone numbers, move countries, stop using social networks, but usually keep using same Linkedin profile over decades.

Also in many social situations such as expos, meetups and such asking for a personal whatsapp or phone number can be a cringeworthy especially if you actually want to followup with some business proposal or solicit your services / asking for referal / etc.

At the same time 99.9% of people will be okay to connect on Linkedin and you will have that +2% trust boost that can be sufficient to make sure your message wont be ignored.

So Linkedin is really worth it as long as you are not using it as social network.