Why is there no time limit?

Time pressure can cause some interesting gameplay. You can't think straight and even simple tasks become stressful. On the other hand it encourages players to hurry up and forget to enjoy the process. It is both good and bad.

In physical escape rooms time limits are mostly implemented for practical reasons. The room needs to be ready for the next group.

We don't need time limits for "escape room in a box" games, and by studying playtesters I found out that a majority of players prefer to play without a time limit. Sometimes I do use time pressure when it makes sense but most of the time you can take your time and enjoy the moment.