A lot of things can look not useful and common at the current time, but have a lot of values in the future. But you can't document every step of your life.

For example, imagine that some friend tell you that his brother is currently working in Singapore and that everything goes well for him and all. But so far you have no relation to Singapore and don't travel so much.

Then 1 year later, you will unexpectedly be sent to Singapore for work and you would highly appreciate a contact there. At that point you remember that the brother of someone is there, but who was it?

You just have to search for 'singapore' in Telegram and you can get easily the reply to your question and so recontact the relevant friend.

Same thing when you are suddenly thinking about buying a Xiaomi phone, and you are wondering who was the friend that told you that he bought one 6 months ago to get his review.

But sure, the best thing to deal with that is to be able to 'backup/export' your history and also being able open/import it in a usable form.

Whatsapp mostly fails on both topics. You can't easily backup, otherwise it would be stored in clear in google drive, in an area that is not even accessible to you.

And then it is a sqlite db with proprietary format for fields, so so far nothing can display it properly offline.

For telegram, they have a good export/backup feature.

I don't know of anytool that would allow to browse your history nicely when loaded offline from backups, but as the format is open, that should be doable.