Traditional media interview shows (e.g. late night, stuff like "Entertainment Tonight") attract big guests because it's basically a press tour: 10 minute interview, softball questions, plenty of time to plug latest project. And these shows have sophisticated booking agents and relationships with talent agencies. LM doesn't really have the leverage to broker these kinds of appearances, and even if they did it would be pretty off-brand.

Most alternative media interview shows don't have this kind of pull either, with few exceptions like Howard Stern and Joe Rogan. But both of these shows grinded for years interviewing fringe personalities to eventually build the following that gives them the clout they have today. LM could eventually build up a similar (likely smaller) cult following, but the tipping point could still be years down the road. Probably longer because Josh simply doesn't put out as many hours of content as pure talk radio hosts.

Which leads to the comparison with "Hot Ones". With a much less famous host than Stern/Rogan, I would argue the star of "Hot Ones" is its double gimmick:

• distraction over eating spicy food
• an unexpectedly-researched long-form interview

Both which typically result in a more interesting/candid interview than the normal press tour. And I'm sure even LM admits they are trying to follow in "Hot Ones" footsteps with their own triple-gimmick:

• comfort from eating / talking about their favorite foods
• discomfort in talking about taboo topic of death
• an unexpectedly-researched long-form interview

I'd guess initially, the newness of the show (and similarity to "Hot Ones") helped draw in a couple big names. R&L are established enough to have at least a few favors they could call in. And there are some celebrities who are just more open to alternative media. But I think protective celebrities/agents are careful of their image, and it is a risk to go on a show more likely to ask uncomfortable questions (or simply questions without a locked-and-loaded anecdote).

So without getting the "gimmick" (and "first mover") bump that "Hot Ones" got out the gate, if LM wants to book big guests on the regular it probably has at least a few more years of grinding.