Replaced my Ortofon Blue stylus today via plug and play swap in seconds

Not all MM cartridges have a user replaceable stylus.  My Grado Sonata does not and neither do the upper end cartridges from them.   I don't know why, other than they want you to buy a new cartridge when it wears out.   There are many others, too - definitely not 99.9%.   Majority?  Probably, but I haven't a clue what the percentages are.   It does appear at first glance the more expensive cartridges do not have a replaceable stylus.  

Clearaudio Virtuoso Wood is a moving magnet that requires you to send it in for rebuild but in reality the stylus can be replaced easily by the end user with very little effort. Makes me wonder if some of the other MM and MI carts that are said to require factory service to replace worn stylus don't fall into this catagory. Enjoy the music

Not all MM cartridges have a user replaceable stylus. My Grado Sonata does not and neither do the upper end cartridges from them.

Grado is NOT an MM cartridge, it’s MI/IM.
Most of them, except for a few models have user replaceable stylus, I have several Grado cartridges, the signature model from Joe Grado is XTZ (this is the best model from Grado, top of the line cartridge designed by Joe) and the stylus is user replaceable!

Do not try to flip the situation, nearly all MM and MI cartridges have user replaceable stylus and they are mid or high output, this is a benefit of MM and MI for decades.

Except maybe for new SoundSmith, a few new Grado models and some new ClearAudio nonsense (which is actually Audio-Technica cartridge body made in Japan for ClearAudio).

Based of the fact that some old Ortofon MOVING COIL, old Sony Moving Coil and old AT Moving Coil have USER REPLACEABLE STYLI, BEING MC CARTRIDGES, I can’t say that Moving Coil have user replaceable styli ! Those carts are exceptions.

So don’t try to do the same for MM or MI, except for a few few models, those type of cartridges are internationally-renowned because of the user replaceable styli, this is why life is easier with MM and MI compared to MC.

The OP is talking about basic Ortofon design and asking about basics.

MM and MI = user replacaeble stylus.
MC = re-tip, factory rebuild or new cartridge.

It does appear at first glance the more expensive cartridges do not have a replaceable stylus.

Some styli cost more than complete cartridge if exotic materials used, such as Beryllium, Boron, Sapphire, Ruby .... cantilevers with advanced profiles. Replacement stylus can cost $500-1000, especially for rare cartridges.

Even brand new Jico replacement styli cost $300-500 easily when it comes to SAS profile and Sapphire, Ruby, Boron cantilevers.

Replacement styli for MM and MI with conventional aluminum cantilever are much cheaper.

If SoundSmith factory stylus replacement is inexpensive (normally 20%)t hen some other manufacturers do not hesitate to change you over 60% of the retail price again when you need only new stylus. The problem is that some cartridge without user replaceable option cost $12000 and when you must pay 60% again they got you! This is the same business model they use for MC, it’s a nonsense in my opinion.

Basically great high-end MM/MI stylus is just about $300 and you can buy as many as you wish for entire life.

Only one addition to Chakster's completely correct remarks: for example, Ortofon asks $236.00 for a new 2M Blue cart, and $204.00 for a replacement stylus.  That's over 80% of the cost for a complete cart, similar to the "re-tipping" fee for an MC.  So I wouldn't say the advantage of replaceable styli is economic, but rather the ease with which an unskilled consumer can effect the replacement...no need to re-align, fuss with nuts and bolts, potentially break delicate wire clips, etc.