Many owners love the center-of-their-universe role because it makes them feel essential, needed, etc. If the owner has a sizable ego (and just about all successful entrepreneurs do) there are few professional scenarios that can feed that ego better than this arrangement. We've observed a number of companies set up where the owner would choose to even sacrifice revenue & profit maximization to retain his or her place as THE crucial player at their company. They often consciously or unconsciously choose to feed their egos over growing their businesses beyond what they can personally manage.
However, in spite of how well that arrangement can seem to work- even over many years- it is an enormous liability when trying to sell the business to someone else. That culture is usually staffed by managers- executives included- who have little choice but to defer to "the boss" for all decision-making. More simply, the owner of that kind of company is often an owner of a business of followers. Chop off the head and the body won't be able to function very well... if at all. To a prospective buyer, this kind of business is loaded with risk because the owner's departure may kill a business unable to stand on its own. This can make the buyer discount your team- including whether they should even keep them as employees after the sale. If you were the buyer, how excited would you be to make a generous offer for that business? If you could discount the ambiguous value of the team, there's little left to influence your offer price but mostly depreciating assets. Allow the sacrifice the team productivity premium and you'll almost certainly end up getting offers below your most modest expectations.
Some owners who have fostered this kind of environment will try to spin prospective buyers into believing that they've long been grooming their replacement. But buyers see right through that spin. The buyer's risk is not in replacing one, lone head with another... it's in the relative strength of the whole (team) who will remain after you leave. A company overly dependent on just a few people- or just one- is a company ready to die should anything happen to those few people or that one. If you've groomed your replacement in an owner-centric enterprise, your buyer would have to take a great leap of faith that that replacement can actually do the whole job when you leave and that your replacement won't quit, die, over-exploit the importance of them remaining with the company, etc. Such risks- real or perceived- adversely slice into the buyer's offer price flexibility. They don't want to pay maximum price AND be required to take such leaps of faith. You mitigate those leaps by installing a planning culture ahead of the sale.
Delegating away all of the fundamental tasks crucial to continuing to maintain & grow a business makes the whole self-sufficient... a company that can continue to prosper long after the founder or owner has departed. It's what the owner should do anyway as most owners would prefer that their baby can live on beyond their retirement... if not for their own legacy, then for the good people they employ (who will appreciate getting to continue to have their jobs after the sale). Spreading those crucial responsibilities around to your team is viewed as diversifying risk for your buyer. Odds improve that the business can thrive after you depart and the new owner doesn't have to worry about any one (or few) players owning too many of the keys that drive ongoing success.
Some ego-driven founders or owners typically detest the idea of delegating their crucial contributions because they either believe that only THEY can do the things they do... or they can't bear the idea of eroding company dependencies on themselves (even if it is by design... to help drive the business sell premium higher). Yet it is exactly what the owner wanting to sell in the next few years should do if they want to maximize their take from the transaction.
Go into the selling process with no planning culture and you definitely will NOT get maximum offers for your company (to the contrary, such owners are always disappointed with what the market is willing to pay for their business). Buyers are just like investors- they love confidence & risk reduction. They want to see that their hard-earned money has a very favorable chance of being returned with a great profit... at the least possible risk. Demonstrate a solid planning culture over a few years PRIOR to when you want to sell your company and your plan projections for the years AFTER the sale will carry great weight with buyers. Make your team into a self-sufficient machine that no longer depends on your personal contributions and the ambiguous value they collectively support works to your benefit in negotiations. The result is much more favorable pricing.