Why not take on SEO promotion?

Question

Search Engine Optimization

Hello, I developed an online store from scratch without frameworks and CMS, and now it's time to promote it in search engines, but not a single SEO specialist takes it for promotion.
One of them told me the following: "The site was created on some old platform, possibly on an old WordPress layout, also the site does not comply with the new promotion rules that have come into force recently and there is no place for SEO in the code, optimize the site, so that it does not load for a long time, make adaptation for different devices and redo the navigation for SEO."

And now I have a question, how do I need to remake my site for SEO, apart from loading optimization and adaptation?
I ask you to help, gentlemen who know, I need advice and an indication of what to fix.

Answer 1

Summary:
The site is made on the knee, that's why they refuse.
What needs to be done:
1st and most important - adaptability , in 2021 without adaptability nowhere, Google and Yandex will gobble up and spit out your site with giblets.
2. Layout - it feels like they tried to sit on BEM, but in the end they got past the chair. Comb it when you make an adaptive.
The surest way : re-implement, put on a ready-made engine, based on the number of orders (wordpress, opencart, etc.). Why: SEO out of the box, already conditionally good code, in which you will not need to dig like in a trash can. > knocking SEO-shnikam.
Now it’s just that the guys from the cargo cult don’t want to step into your swamp, it can come out more expensive for themselves.

Answer 2

So you are those who told you and ask
Well, or read at least one book on SEO, it’s stupid to approach this without elementary complex knowledge

Answer 3

In principle, colleagues have already painted everything. And in detail. I can only add that people are unreasonably addicted to self-written platforms for relatively small sites.
And self-writing is always more expensive and more difficult to manage.
It is better to take a ready-made CMS

Answer 4

Any site can be promoted to a certain level - you won't be able to take over the world.
Often SEOs are just "stupid" and want to pump the dough, from this, they take something that is potentially easy to promote_)