After the changes from T76426, we should consider moving the blockquote tool to another section of the toolbar.
Previously, VisualEditor treated blockquotes as "single-line" elements, same as headings or paragraphs. This caused issues when pages contained multi-line blockquotes (duh!). Now that they are multi-line and they can contain multiple other elements (e.g. headings, paragraphs, but also e.g. lists), grouping them in the toolbar with single-line elements is weird.
Quoting some comments from the discussion there: