Why is there a word limit for texting?

70 Chinese characters, or 140 western characters.

This is either a technical reason or a design limitation, because generally speaking, 70 words can explain one thing clearly. Such limitation can save storage space, reduce design and production costs and improve reliability.

Now technology has advanced, but this limitation has not disappeared, but EMS has appeared. In this way, short messages larger than 70 words can be split and sent, and if the other party supports this technology, they can be combined into one short message.