One the surface and first glance I tend to agree. But with MiLB now under the MLB roof the push the last few years has been stadium upgrades a mandated by the Commissioner's office. Stadium size, team amenities and so forth. I also think that the minor league players are now somehow tied into the players association.
A company owning the rights to several teams opens the possibility of negotiating vending prices downward, possibly consolidating some of the front office work (accounting, national or regional advertising sales, etc). Maybe the ability to entice concerts or other draws to several venues rather than just negotiate each venue separately.
Minor league stadiums are usually owned by the community and leased to the team for X number of games so if a community wants to continue to host a team at their venue they need to keep the facilities up to standards. (I'm seeing that now in Richmond,Va where discussions over financing upgrades for the minor league club continues despite missing the deadline (again).
I get the downside, having spent nearly 50 years either working or closely watching the broadcast industry (radio) to anticipate the pitfalls.
A perfect world would have the parent clubs own all their development teams. That's never going to happen in my or my 12 year old grandson's lifetime