I think the opportunity to post inline images on a forum such as this one does more harm than good, much like the option to specify the font size and colour. Disallowing those would significantly reduce the problem you describe. One can always refer to images, videos etc. by linking to them.
Not all people like to click here and there redirecting their attention everywhere and then forgetting everything, some people like everything laid down in one piece on one page, some prominent forumer here use this variation of font size and colour to emphasize and organized certain thing in their posting so disallowing probably is not acceptable, you can always download
lynx browser and browse this forum in text only if you have strong dislike of all the flashy stuff and different size of font.
its probably bad in your view, but on the other hand some of the information like price movement cannot be describe with words in plain text only, you need chart in graphic form with variation of colour and font size to present it properly.