tikhonov1 Let me explain a bit here with the concept of article view in Purity IV template.
1/ Joomla recommend article content should include introtext + readmore + fulltext. Category blog page, Joomla module will take intro text of articles to show so if you don't have introtext, it will show full text and it will not look nice. And that's why we recommend the same.
2/ As concept of Purity IV template, the article detailed page will show Title, Article Info, Introtext, image, fulltext, .... and when there is no introtext added, as I mentioned above, Joomla will consider fulltext as introtext as well but the loadmodule script will not work in introtext so it displays plain text there.
And due to design, the section before 'readmore' tag is introtext which display fully. While in fulltext part (after 'readmore' tag) the main content will include 2 sections: sidebar of article on the left and the main content on the right. The left sidebar will show author info / social share buttons, .... so the main content doesn't in full width there.
Each template has its own concept for different layout, the same with Purity IV, so it's not ideal to compare with default Joomla template as basically they are different templates 🙂 . If you want to have same view like default template, you can customize the override file:
/templates/purity_iv/html/com_content/article/default.php
/plugins/system/t4/themes/base/html/com_content/article/default.php
I hope this makes senses.
