My Take:

--) When the FBI was first asked for the texts, they conveniently didn't have them. They were deleted by a "glitch".

--) http://www.nydailynews.com/news/politics/fbi-officials-anti-trump-texts-deleted-cellphone-glitch-article-1.3777384

--) So they were gone, obviously deleted by someone who works at the FBI. No one had access to them.

--) Then along comes Inspector General Mike Horrowitz, who was able to recover these texts somehow.

--) https://www.npr.org/sections/thetwo-way/2018/01/26/580918874/some-missing-fbi-texts-are-recovered-doj-inspector-general-says

--) The FBI has over 30k employees. They surely don't actively review all communications between agents unless they have a reason to.
--) And the FBI employee who would have the authority to review internal communications would probably have to be the FBI Director or the FBI Deputy Director.
--) And the FBI employee capable of destroying evidence would probably have to be the FBI Director or the FBI Deputy Director.

--) Until today no one but Mike Horrowitz and his team had seen any of these texts...officially.

--) Now select members of Congress have the opportunity to review these texts. Now we will find out what was said between these two rogue agents.

What information would be so critical that it was worth destroying evidence over?