There is a Buddhist quote which states, "I never see what has been done; I only see what remains to be done." But learning can be overwhelming if we only look forward.
Drupal 8 has dramatically changed the process of creation of custom formatters and widgets. If in Drupal 7 this could have been done with hooks usage, then in the new version this process is similar to Ctools plugin writing.
When building a site you want to make sure that it can handle the expected (and even unexpected) load that might incur through the traffic that the site will receive.