✔ Alternative analogue of channels "Telegram" in blockchain

[0xbt]

Example:

1. A group of people who need their own encrypted channel.
Let's call it "XXX".
This channel "XXX" corresponds to the real Ethereum address (created for this example):
0xAde7663DB354fb71e46D3D3dcdB0BaBcAd89bF76
2. Each "member" of the given channel is given a nickname, which also has its own specific Ethereum address.
3. The group member sends a message to the channel (you can send images) - TxHash:
https://etherscan.io/tx/0x57b987f3d5ad5c65fb15435ad8632ba187684a9ce5e6957f1485e3f19cba35fe
Click Convert To Ascii and follow the link.
(the time of this transaction was 1 minute)
4. The key-password of this channel for decoding is as follows:

In the town where I was born
Lived a man who sailed to sea
And he told us of his life
In the land of submarines
So we sailed up to the sun
Till we found a sea of green
And we lived beneath the waves
in our yellow submarine

We all live in a yellow submarine
Yellow submarine, yellow submarine
We all live in a yellow submarine
Yellow submarine, yellow submarine

Copy and paste into the password window. Result you will see for yourself.
5. The participants monitor «XXX» channel.

Plus:
- All participants are anonymous (for other persons).
- The channel can not be closed.
- No licenses and state registrations are required.
More precisely, they can not be imposed on this channel.
- Services hosting providers are not required.
- Third-party applications are not required.

Minuses:
- Fee for Gas. In this example, it was: 0.000140962 Ether ($ 0.09)
- Not everyone can use this tool, but this is a plus.
- Data transfer limitation: max ~ 45 kb.

To send a message in this example, MyEtherWallet and MetaMask were used.
The time taken to send this message took 2 minutes.

Of course, there are other drawbacks here.
But this method works.

What other alternatives can you offer?