So here's what the concern is..

Let's say I relate a task with a contact and this contact has a parent account named ABC

Therefore, indirectly, the task will be associated with the account ABC as well and will show up as an associated record under ABC

However, if the primary account of that contact is now changed from ABC to another account say PQR, the task shows up under the new account PQR

It no longer appears as an associated record of the account ABC

Now, there is a problem with this behavior and I would like to illustrate that with help of a scenario as follows

Let�s say in my CRM instance, there is a contact named Niel who works for Microsoft and therefore, I keep Microsoft as Neil�s parent account

While he is with Microsoft, I create a task that I associate with Neil�s record

Now, if he later joins another company, that task would now show up as an associated record of the new company

However, that task had to do with Neil while he was with Microsoft and if this task gets associated with a different company, it wouldn't make sense

It definitely does not look ideal