Analyze the following business scenarios to determine their suitability for using Paid Advertising Channels:
- Scenario I: A new app aiming to quickly gain market share in a competitive tech industry.
- Scenario II: An online boutique specializing in unique, handcrafted accessories, recently launched.
- Scenario III: An established e-commerce platform launching a high-value product line.
- Scenario IV: A niche hobby blog looking to grow its audience steadily and organically.
Identify which scenario(s) are most appropriate for Paid Advertising Channels.