Some of them (atlaskit, MS fabric, Jetbrains, vmware etc) are geared towards building an integration withing those company's products. Whilst they can be used independently (without assets in Fabrics case, and other restrictions in the others), my take is the Evergreen (and ant, etc) are geared towards isolated products, similar to Bootstrap.
If you're building an addon for use in an Atlassian product, or an Office 365 product, these are a great way to stay consistent with the host application's look and feel.
Some of them (atlaskit, MS fabric, Jetbrains, vmware etc) are geared towards building an integration withing those company's products. Whilst they can be used independently (without assets in Fabrics case, and other restrictions in the others), my take is the Evergreen (and ant, etc) are geared towards isolated products, similar to Bootstrap.
If you're building an addon for use in an Atlassian product, or an Office 365 product, these are a great way to stay consistent with the host application's look and feel.