Time-based tokens, i.e., KOLs tokenizing their time, have recently resurfaced. Although various attempts have been made in the past, none have taken hold yet.
Instead of time, I have always wanted to optimize reach. LinkedIn, X, provides this ability, but the barrier is too low, resulting in a lot of spam, making them unusable.
Here is an idea for a platform that allows serious people to reach others.
A famous person (KOL) connects his X (or LinkedIn) to the platform, verifying who they are. He then sets a price for people to message him, say 1 or 0.1 BNB.
Anyone can message him/her by paying that amount first. If the KOL does not respond within 5 days, 50% of the paid amount is returned to the requester. There is still a cost to the requestor, which deters spamming and encourages them to write the message effectively.
The KOLs are incentivized to respond. They get paid 50% more.
Defaults based on my personal preference:
Max message length should be limited to 2000 characters, roughly a two-pager.No images. No attachments. (No virus downloads)
The requester can include his contact info in the message. If the KOL contacts them directly, he (and the platform) gets paid 50% less.
If the KOL wishes, he can reply with his contact info, and then the conversation can continue on a free messaging app.
The platform charges a 10% fee for all transactions. Payment-wise, the requestor pays crypto to the platform, which then splits 90% to the KOL’s provided address. 
No new token is needed.
No time-based tokens.
Hopefully, there is enough demand for such a platform to make it a sustainable business.
This might be a good way for KOLs or professional consultants to get paid for their responses.
I would use a platform like this. I will donate the crypto I receive to a charity. This helps filter out only serious people to reach me. I may move the conversation off the platform when the other party has something serious to offer, return the payment, or even give a bounty (for security tips, etc). I will then be able to open up my DM to everyone and adjust the price over time based on how unpopular I am.
This model doesn't solve all problems. Not to be arrogant, I'd imagine many scammers will be willing to pay 1 BNB to reach me.
YZiLabs may invest in a project that develops a good MVP using BNB/BSC as the primary payment option. It should take a few days/week of coding and a security review. I will be a first user, provided the platform is secure enough.
X, Linkedin, or Square could build this as a feature, but big companies move slow. Might be faster with a new site.
Just an idea for the weekend.