This is what the MBCBP is:

Hey, how about we lock your 401k excess cash in a vehicle that underperforms the s&p for the next 30 years so you can defer your taxes until retirement? Sound like a good deal to you?

​​​​​Oh, you wanted to invest the excess into your Roth IRA, real estate, businesses, or your personal brokerage account? Nope! Not allowed.