Why does the typecho routing table need to be stored in the database, and why does each URL need to be written in this form?

After reading the source code of typecho, the structure is quite compact and seems to have heavy Java object design ideas.
But I have great doubts about the setting of the routing table.
The current way of writing basically fixes this structure. Why not make it configurable by the user, such as saving the routing table in a configuration file, or implementing the automatic routing function. Is it to keep it simple?
The current way is that if I want to do some new development, it seems that I can only do it through plug-ins.
Let’s not talk about this issue for now

My problem is the following routing table
'attachment' =>

<code>array (size=6)
  'url' => string '/attachment/[cid:digital]/' (length=26)
  'widget' => string 'Widget_Archive' (length=14)
  'action' => string 'render' (length=6)
  'regx' => string '|^/attachment/([0-9]+)[/]?$|' (length=28)
  'format' => string '/attachment/%s/' (length=15)
  'params' => 
    array (size=1)
      0 => string 'cid' (length=3)</code>

Looking at the code, it seems that the url field is not used, so is this just to prompt that the link is in this mode? Functions similar to comments
Or are there some functions that I neglected to notice? If you know more about them, please let me know