For the 40b no. You can see when you get there that some cabinets are made of that pressed board same as the stands sold for aquariums.
Then theres other cabinets that feel alot stronger and are made from better materials. The one for the 40b was pressed wood and had no issues
My cousin set up a 110g 4ft long and a 4ft vanity cabinet from seigles that was made from non pressed wood, you can see the diference on his vanity.
On the 6ft long i have now. I did reinforce it. I placed the countertop on 2x4 so the weight was actually on the 2x4 and the cabinit was sitting holding minimal weight.
Not sure that makes sence.