midnightexpress,
If you want to learn about how written English evolved, the best 'one-stop-shop' is the Children of the Code www.childrenofthecode.org.
A brief potted history - late 14th/early 15th century, the French-speaking King of England instructed his French & Latin speaking court scribes to devise a written language for English (which was not actually one language but a hybrid of different languages) which they did using the Latin Alphabetic Code.
Latin - 26 sounds + 26 letters = written Latin
English - 44 sounds + 26 letters + 70 common spelling rules = written English.
Arguments on how best to teach written English started mid-15th century.
Most common form of teaching written English from 15th to 19th century, direct, explicit instruction in basic code with limited sight word guessing and memorising.
1950's - beginning of scientific research into effective beginning reading instruction.
1960's & 70's - Extreme form of sight word memorising and guessing plus rejection of direct,explicit, systematic teacher-directed instruction named Whole Language becomes fad-du-jour.
Whole Language re-names itself every time it's contents become known and discredited; constructivist, child-centred, discovery, hands-on, multicueing, 3-Searchlights, 4-resources etc.
80's onwards - Reading Recovery, the remedial arm of Whole Language (more of what didn't work in the first place) becomes entrenched in Australia & New Zealand and highly present in USA, Canada & UK.
90's - results of Project Follow Through are published providing conclusive proof that direct, explicit, intensive, systematic teacher-directed instruction is more effective than child-centred strategies.
Results ignored by The Blob.
80's onwards NICHD & others set up multiple scientific longtitudinal studies to examin effective beginning reading instruction.
2000 - meta-analysis The National Reading Report published. Results ignored by The Blob.
Teacher Training
There has never been a time when the teaching and learning of written English has been 'perfect'. Prior to the 50's, the only qualification necessary to teach primary was that the teacher could read themselves and they were still breathing.
50's & 60's saw attempts to improve teaching by creating 1 & 2 year 'teacher training colleges'. The teachers teaching the teachers were from the pool of 'can read themselves and are breathing' experienced teachers. Some very good, some terrible.
70's onwards - attempts to improve teacher training saw the teacher colleges re-created overnight as University Schools and Faculties of Education (Ed Schools) providing 3 & 4 year degrees in 'Education'.
'Perfessors' of Education created from the pool of can read/can breathe existing teachers.
These Ed Schools became closed-shop 'gatekeepers'. No-one allowed into the teaching profession without being accepted into and approved by the Ed Schools.
Late 20th century onwards - Data from USA, UK, Australian & New Zealand Ed Schools informs us that all Ed Schools embrace the 'child-centred' philosophy and provide none to little information about scientific evidence based instruction.
Mid-20th century onwards - Spending on Education skyrocketed with costs of 3-4 year University degrees producing countless teachers with no knowledge of effective instruction resulting in increased failure and under-achievment in students and massive increased spending on remedial instruction for students and additional training for teachers. Lobbying for smaller class sizes and extending compulsory education creates massive increases in teacher numbers. More teachers going through more expensive but misinformed training results in more increases in costs.
Reaction is to spend more on what has been proven not to work while ignoring the evidence of what does work.
You say, "So it's not that simple, is it?" Actually, the only simple thing about effective instruction is that we know what DOESN'T WORK!
Any programme that embraces the 'child-centred' philosophy is less effective than any programme that requires teacher-directed instruction.
Any programme that allows beginning readers to guess and/or memorise is less effective for all children than any programme that teaches synthetic phonics 'first and fast'.
Any programme that prioritises spoken language over written language is going to have a neutral effect on most advantaged children but will have an exponentially larger negative effect on disadvantaged children.
I suggest you read Zig Englemann on how time is the enemy of disadvantaged children.