It is possible to link to all existing collection items via the list offered at the page link option in rich text links, wherever this rich text field is placed. But the collection items are not available from the same page link option in text links and link blocks, so this needs to set a manual external link to specific collection items, what at least enables this linking.
But during development phase the final domain is regularly not conncected. This needs to renew all manual links of this type during the release of the site, what means additional work, to do and potential failures. Also, this can break links, if the url of collection items would be changed.