The definition of lineage changed because the purpose of lineage has changed. All of the following is my opinion, if I mess some facts up, please correct me.
Naming corals went mainstream with Tyree and his LE corals (the first named coral was Tubbs Blues btw, something the owner was not happy about just for a quick fact). Tyree was naming corals that came in and held their color and their morphology and would be easy to propagate. It was a way for people to know that it was an aquacultured coral and that coral was not just pulled off of the reef and could change colors or just straight up die on them. Tyree was sent these corals (that is right he never bought them) and he would grow it out and observe it and then if it held true it would be named and release.
On top of this you had sites like coralpedia who were trying to come up with a "dictionary" of corals (obviously focused on zoas). To get your coral named you had to send in pictures, daylight and actinic, which they would then compare to know morphs. If is was something new it was given a name and a new entry, if it was not then that did not happen. Again this was to keep track of certain zoas and how they grew and easily be able to talk about husbandry. For example, a purple people eater likes lower light in a tank, this is known because that coral has been around and propagated for a while (fun fact, they came in brown and colored up).
So what happened? Greed. The downfall to Tyree is that people wanted names so that drove up price. He was not hacking apart wild colonies, he was aquaculturing corals which led to a slower supply. Obviously slow supply, high demand and the prices went up (Miami hurricane went for 225$ an eye back in the day). Other vendors noticed this and the name game blew up. Every coral had to have a name or it was not a good coral. Some of the good guys still kept the aquaculturing goal in mind and made sure they were selling good stable corals. Other turned into chop shops, bringing in corals, taking a good picture, slapping a name and high price and wash and repeat.
Now we have his the next wave which is hobbyist naming. We hobbyists have a much better source of wild and maricultured corals then ever before. Plus with sites like R2R and social media, we have access to pictures and corals from all over the world. Basement guys are getting wholesaler license and bringing in rocks and rocks of corals to sell. So now that hobbyists have more access, they are jumping on the game as well. Again, driven by greed they are getting mariculured corals (which today are hundreds of times better then they were even a few years ago) and naming them and trying to make a quick buck on unsuspecting reefers.
Now the use of lineage has changed. First is was to prove it was aquaculutred, now it is being used to prove you paid a lot of money for something. That is why people are so touchy about lineage, it is just to protect their "investment" which is just a completely foolhardy opinion to have on corals.