Short answer: yes. Not because it is trendy. Because after you send a link you do not control the device. Purchasing is on the floor, a leader is in a car, a candidate is on the metro. They will not go home to a desktop before they decide whether to reply.
Tablet previewResponsive is not “the page can shrink.” It is one site that still finishes the job at every width: understand the business, find a product, tap phone or form. Cram a desktop site onto a phone — unread type, untappable nav, a hero that pushes the form three screens down — and you have no mobile site.
Search engines also score mobile experience. Unusable on a phone hurts index and rank, and compounds less. See Being Found in Search Is the Website's Compounding Return. Inquiry conversion is especially fragile on phones: tiny buttons, captcha popups, too many required fields cut the last step. See How a Website Turns Strangers Into Inquiries You Can Follow.
Some think their buyers “sit at desks, so they use computers.” Even if the first contact uses a desktop, the next person on the chain may open your link on a phone. Referrals, tender attachments, Moments cards — all mobile scenes. Why card-based selling struggles to pass a decision chain: Why Business Cards and Moments Make Lead Gen Harder.
In delivery, make home, products, cases, and contact usable on a small screen first. Do not chase every decorative animation. Compress images so the first screen is not a 4G half-minute wait. Cost is higher than desktop-only, far lower than a second mobile site later.
Finish one inquiry on a real phone before you say it is adapted
A lot of so-called responsive is only a hamburger. Open a product page and the spec table slides until units vanish. Tap phone and dialer does not open. Form dropdowns hide behind a fixed footer. Those belong in acceptance. Also watch WeChat’s in-app browser: some scripts or captchas fail there, and buyers arrive from Moments. Test at least one iOS and one common Android — not only the designer’s desktop preview.
Images and type also shape mobile. An oversized hero spins on the metro and visitors leave. Budget: What a Corporate Website Costs and How Long It Takes. DaXi corporate sites ship responsive by default. To review an old site, go to the corporate website service page, or see Redesign the Old Site, or Rebuild It. How inquiry conversion is designed on phones: How a Website Turns Strangers Into Inquiries You Can Follow.
Also keep this in mind
Landscape tables, PDFs, and map buttons are three more mobile traps. Spec tables can become cards on a phone instead of shrinking unreadably. Mark PDF page count and file size. One-tap maps should open the system map. Then you may say it works on site.
Chat widgets, side floats, and cookie bars stacked on a phone will cover Submit. Before launch, open Contact on a real device and cut floats to one.
Type on phones should stay in a readable range. Line length should not fill the screen to fatigue. That is readability, not decoration, and it decides whether they will fill a form.
Test landscape video and portrait forms. Accepting only the designer’s vertical phone frame misses purchasing reading drawings on a tablet.
At acceptance, turn off the desktop emulator and tap the tiny-looking icons on a real phone. Simulator pass, device fail is the most common responsive acceptance leak.