Do you know how stupid that sounds? As a LB or any position on defense. Your job is to tackle the ball carrier, not dance with offensive lineman.
You are partially correct and the others who are saying it is his job to occupy a blocker are partially correct. It all depends on the defensive play call, individual responsibility, and offensive scheme. Each D player is responsible for a gap and plays that gap to either spill (force the ball carrier outside) or squeeze (force the ball carrier inside) based upon their reads and where the help is. This can be different each play depending on the blocking scheme of the offense.
For example, with Joe (and I don't know what he reads specifically: backfield, center-guard, cross read in shotgun, etc), if his first key is the strong side guard (again hypothetical, I'm not in the practices), the guard could block down on the DT, base block to Joe, pull either direction, reach block to get leverage outside, zone block in unison w/ the rest of the line, or pass set.
If that guard pulls the other direction, that turns Joe into the attacker over top of the defense. That guard is designed to kick out a DE or lead up on an OLB most of the time, so Joe's responsibility as his gap now shifts with the guard is to trail it, fight over top of another blocker if he's coming to seal Joe off, and tackle the ball carrier if he cuts back.
If the guard blocks down on a DT and the gap is open, Joe fills the gap and will typically meet a pulling or trapping lineman, fullback or even TE nowadays. His job then is to close that gap and force the ball carrier to his help, OR if he's athletic enough, stun the blocker, fight off while keeping his gap integrity and make the tackle (i.e. The good old Oklahoma drill).
Another example using Rochelle. If he's on the end of the line and his OT or TE block down, there's likely a guard pulling to kick him out. A lot of coaches and schemes call for him to "wrong arm" the puller and cut into the designed gap forcing the ball carrier to the OLB MLB or safety. But, with everything, if he's athletic enough, he blows through the puller, knocks the RB off course and gets a TFL.
Other times, a specific blitz, stunt or slant are called and it's damn the linemen, get penetration and make a play in the backfield. That's a risk reward call.
So both are correct. But I'll say it again, these situations are based on my playing experiences in D3 in college and then being a D coach and later coordinator in D1 high school. I played in a 4-3 base defense with multiple fronts and a dime and bear package. We were heavy on the zone dog or fire zone blitz schemes which I see at times watching ND. I don't have the playbook and am not in the meetings or practices so my hypothetical situations are based solely on my own experience.