(See this post for an explanation of what’s going on here.)
“Though this technique is often given Shiki’s term shasei (sketch from life) or shajitsu (reality) it had been in use since the beginning of poetry in the Orient. The poetic principle is ‘to depict as is.’ The reason he took it up as a ’cause’ and thus, made it famous, was his own rebellion against the many other techniques used in haiku. Shiki was, by nature it seemed, against whatever was the status quo. If poets had over-used any idea or method his personal goal was to point this out and suggest something else. … Thus, Shiki hated word-plays, puns, riddles – all the things you are learning here! He favored the quiet simplicity of just stating what he saw without anything else having to happen in the ku.