If someone is working on something for a long time, they can explain what part of it they worked on, whether they need help, whether they're blocked, whether they need to adjust expectations, and so on. Long running tasks are a necessary evil, not the default state of the world, as they make planning work difficult.

Giving people time to express that they are being blocked or that they need help with something increases the chances that they will feel empowered to ask for help or to be unblocked. It also aids in accountability and ensuring that people are getting their work done on time and as agreed with stakeholders, as well as giving other team members an opportunity to mitigate any such issue.

On the other end, formalizing that it is short prevents it from turning into an unexpected retro or venting session or long-winded technical discussion better left for some other forum. Everyone should be able to give a quick update before any member of the team loses interest.

There are reasons behind all of these things, and as aware as I am that not everyone agrees with every tenet of every leadership strategy, the "standup" as commonly formalized is actually really solid and I would expect a good reason not to employ it in the way that it typically is.