[Chris is me]

Using bearing blocks doesn't really have anything to do with obstacles on the field, or being more able to drill a hole in aluminum plate versus tubing, or even ease of maintenance.

First, COTS bearing blocks have the advantage of a precision bore to retain bearings - for teams without machining resources, this is simply the only way they're going to pull off a reliable live axle drivetrain.

Bearing blocks are most often used when you are using a sliding block tensioning system. A sliding bearing block tensioning system moves the axles away from the gearbox until the power transmission is properly tensioned. This allows for perfect tension, adjustable over time, without any loss in efficiency as would be the case with a chain idler or other system.

Additionally, single piece bearing blocks allow for perfect concentricity between the bearings. This improves efficiency greatly. Double piece bearing blocks such as the VersaBlock rely on counterbores and other geometric features to ensure concentricity.