On the client side, the wallet would've prevented it and the user would have to explicitly specify that they want to embed a message through the use of OP_Return.
But blockchain is a ledger, not a messenger. These coins shouldn't be burnt for this purpose. Also, they're burn addresses like
1Lets1xxxx1use1xxxxxxxxxxxy2EaMkJ
1fuLL1xxxx1power1xxxxxxxxxxzatvCK
1of1xxxxx1anonymity1xxxxxxxz9JzFN
1See1xxxx1memo1xxxxxxxxxxxxxBuhPF
1dot1xxxxx1sv1xxxxxxxxxxxxxwYqEEt
1topic1xxx1hmwyda1xxxxxxxxxvo8wMn
1xxxxxxxxxxxxxxxxxxxxxxxxxy1kmdGr
They can be used as a message too.