Rich Text/HTML boxes allow you to add text, images, tables, JavaScript. etc. While Rich Text boxes give you editing and formatting freedom, any links you include will not be considered assets and will not be included in the Link Checker tool.
Create a list of databases using the Databases A-Z list that is maintained by your LibGuides Team. You won't have to worry if URLs, coverage or names change because WE will revise databases centrally.
Do your guides contain multiple links to one URL -- like CLP or the CMU homepage? When you create a link asset, you can reuse it again and again. If a URL, name or description changes - you only have to change it once! PLUS link assets are included in the Link Checker tool.