Because he was an intelligent, devout reader whose culture, while certainly not the same as that of the authors of Genesis, was closer to it than yours is. He spent more time in the scriptures than you or I ever will, and he was probably the most influential Christian interpreter of the Old Testament in the early centuries of Christianity after the NT authors. If his obvious, natural reading of the text is diametrically opposite to your obvious, natural reading, then it might trigger just a pinch of humility about your own ability to be the arbiter of what the text means.
Neither has anything to do with being a competent reader of Hebrew scriptures. (And the former isn't really accurate -- if you count Origen as proto-Arian, you also have to throw out people like Tertullian.)
For me, reading the early chapters of Genesis and concluding that it's supposed to be a literal, historical account of anything is mind-boggling. A wide range of modern scholars would agree, including Roman Catholic and Reformed scholars and theologians and everything in between.
Do you believe in Noah and the flood as a historical event? Christ and Peter both refers to the event. How about God creating man and woman? Christ did. Paul compares Christ to the first Adam. Jude talks about Enoch.
The first eleven chapters are referenced over 65 times in the New Testament (not to mention the Old Testament). And these references are not in some poetic fashion but taken as historical fact. What is mind-boggling is how Christians can accept the New Testament while dismissing the first eleven chapters of Genesis as some fairy tale. I'm not sure how they could make heads or tails out of the scriptures. As for the Reformed scholars your talking about, I'm not sure who your talking about but they're probably not worth their weigh in salt. But, quite frankly, there aren't very many good "modern scholars" these days.
1. Matthew 19:4 Created male and female (Genesis) 1:27, 5:2
2. Matt. 19: 5-6 Cleave to his wife; become one flesh 2:24
3. Matt. 23:35 Righteous Abel 4:4
4. Matt. 24:37-39 Noah and the flood 6:1-22, 7:1-24, 8:1-22
5. Mark 10:6 Created male and female 1:27, 5:2
6. Mark 10:7-9 Cleave to his wife, become one flesh 2:4
7. Mark 13:19 Since the beginning of the creation which God created 1:1, 2:4
8. Luke 3:34-36 Genealogies: Abraham to Shem 11:10-26
9. Luke 3:36-38 Genealogies: Noah to Adam to God 5:3-29
10. Luke 11:51 Blood of Abel 4:8-11
11. Luke 17:27 The flood came and destroyed them all 7:10-23
12. John 1:1-3 In the beginning 1:1
13. John 8:44 Father of lies (Satan) 3:4-5
14. Acts 14:15 Who made the heaven and the earth 2:1
15. Acts 17:24 God made all things 1:1-31
16. Romans 1:20 The creation of the world 1:31, 2:4
17. Romans 4:17 God can create out of nothing 1:1-31
18. Romans 5:12 Death entered the world by sin 2:16-17, 3:19
19. Romans 5:14-19 Death reigned from Adam 2:17
20. Romans 8:20-22 Creation corrupted 3:17-18
21. 1 Corinthians 6:16 Two will become one flesh 2:24
22. 1 Cor. 11:3 Head of the woman 3:16
23. 1 Cor. 11:7 In the image of God 1:27, 5:1
24. 1 Cor. 11:18 Woman from man 2:22-23
25. 1 Cor. 11:9 Woman for the man 2:18
26. 1 Cor. 15:21-22 By a man came death 2:16-17, 3:19
27. 1 Cor. 15:38-39 To each … seeds of its own (kind) 1:11, 1:21, 1:24
28. 1 Cor. 15:45 Adam became a living being 2:
29. 1 Cor. 15:47 Man from the earth 3:23
30. 2 Cor. 4:6 Light out of darkness 1:3-5
31. 2 Cor. 11:3 Serpent deceived Eve 3:1-6, 3:13
32. Ephesians 3:9 Created all things 1:1-31, 2:1-3
33. Ephesians 5:30-31 Cleave to his wife, become one flesh 2:4
34. Colossians 1:16 All things created by Him 1:1-31, 2:1-3
35. Colossians 3:10 Created in His image 1:27
36. 1 Timothy 2:13-14 Adam was created first 2:18-23
37. 1 Timothy 2:14 Woman was deceived 3:1-6, 3:13
38. 1 Timothy 4:4 Everything created by God is good 1:10-31
39. Hebrews 1:10 In the beginning God made heaven & earth 1:1
40. Heb. 2:7-8 All things in subjection under man 1:26-30, 9:2-3
41. Heb. 4:3 Works were finished 2:1
42. Heb. 4:4 Rest on the seventh day 2:2-3
43. Heb. 4:10 Rest from His works 2:2-3
44. Heb. 11:3 Creation of the universe 1:1
45. Heb. 11:4 Abel offered a better sacrifice 4:3-5
46. Heb. 11:5 Enoch taken up 5:21-24
47. Heb. 11:7 Noah’s household saved 7:1
48. Heb. 12:48 Blood of Abel 4:10
49. James 3:9 Men in the likeness of God 1:17, 5:1
50. 1 Peter 3:20 Construction of the Ark, eight saved 6:14-16, 7:13
51. 2 Peter 2:5 A flood upon the ungodly, eight saved 6:8-12, 7:1-24
52. 2 Pet. 3:4-5 Earth formed out of water and by water 1:6-7
53. 2 Pet. 3:6 The world destroyed by water 7:17-24
54. 1 John 3:8 Devil sinned from the beginning 3:14
55. 1 John 3:12 Cain slew his brother 4:8, 4:25
56. Jude 11 The way of Cain 4:8, 4:16, 4:25
57. Jude 14 Enoch, the seventh generation from Adam 5:3-24
58. Revelation 2:7 Tree of life 2:9
59. Rev. 3:14 Beginning of the Creation of God 1:1-31, 2:1-4
60. Rev. 4:11 Created all things 1:1-31, 2:1-3
61. Rev. 10:6 Who created heaven . . . and the earth 1:1, 2:1
62. Rev. 14:7 Who made the heaven and the earth 1:1, 2:1, 2:4
63. Rev. 20:2 The serpent of old, who is the devil 3:1, 3:14
64. Rev. 21:1 First heaven and first earth 2:1
65. Rev. 21:4 No more death, sorrow, crying or pain 3:17-19
66. Rev. 22:2 Fruit of the tree of life 3:22
67. Rev. 22:3 No more curse 3:14-19
68. Rev. 22:14 The tree of life 2:9