Despite all the UX methodologies, tools, procedures followed etc.; Design is all about “Perception” I believe.
No two persons in the world have a same perception towards anything. So, on what basis the Industry people(UX) would decide which method is best, which design methodology to be followed, which design looks better when doing it in a certain way???
Well, the ultimate goal of good UX is to design something that can be universally understood and easy to use.
Something to keep in mind when designing for a positive UX is your audience.
Researching who will be using the application you are designing:
What is their age group?
Are they Male?
Are they Female?
What colors best suit people who cannot see certain colors?
What is simple enough to use and visually communicates knowledge to your selected audience?
You are correct, no two people have the same opinion about design elements. Looking at resources can be helpful for deciding what to design for those audience(s). Analytical research can show which design principles to enhance, and other design principles that do not nourish your UX.
Yes and No 
All design is about perception in whatever medium you’re working in, like visual, sound or touch. Perhaps no two people have exactly identical perceptions of the medium, however many have very similar perceptions and interpretations based on biology, psychology, and cultural factors.
For example, the Gestalt Principles of Design are based on psychological principals of how humans interpret visual information. At least for a visual medium they apply consistently to most humans regardless of preference or other factors like culture.
Cognitive biases are another area that affects the perception of designs consistently across many users. Some are culturally based, but definitely apply consistently to large groups of users.
I’d also caution that perception is important in how it directs or inhibits action. In the end, everything’s worth what it buys your audience of interest.
Even if differences exist in perception, there tend to be groupings that relate back to how a service or good interacts with people’s life demands, and those groupings result in similar actions. It’s not inscrutable. You need to ask and get an insight into why those groupings happen.
Pragmatically: even if all you’re doing is making your customer feel more welcome or included, you’re reducing turnover & friction within the system based on complaints, and increasing the cost to competitors to peel away customers.
So I’m just going to run with this as a thought exercise. Let’s assume that design is manipulation of perception.
if we posit that no 2 people have the same perception, and we’re trying to achieve a particular goal, then our inputs, onboards, etc, have to be open to numerous perceptions, aka variance. variance in messaging, in framing, patterns and visual metaphors, recall, etc.
however we’re often reminded to limit the audience in order to increase the overlap between people’s perceptions and allow us to decrease the variance. the ‘arrow head’ idea - that the tip of an arrow is ultra narrow and concentrated. after market penetration you may expand as needed.
if we flip this and decide not to narrow our audience because our solution could solve the same problem for across multiple “industries”, it likely will not have the particular impact required to change one’s perception. because that’s what design really is, it’s not about trading problems or making pretty things.
it may not have the impact to change perceptions for a number of reasons eg: intelligence is domain dependent; trust is build through familiarity, not abstraction; marketing budgets are finite.
there is also an assumption here that a design solution needs to appeal to many people in order to be considered a success. in order to change perceptions, growth sort of implied.
so in order to design something that grows, we’re talking about idea transmission. or to use a more human phrase, we might call it something like Advocation.
to put it a different way a la Design Twitter: