With Mosaico templates, it isn't that difficult to reach Gmail's limit of 102kB with an email newsletter, after which your email message is clipped and not displayed in full. This is unfortunate in itself, but it also breaks open tracking as the tracking pixel is only embedded at the very end of the message and thus isn't fetched unless you open the reader clicks "View entire message".
Would it risk too much ugliness for those who don't display images to put the tracking pixel at the start of the message?